The Saiya-jin Saga starts off with the arrival of Raditz. A farmer goes to investigate the area where the space pod landed and sees a muscular figure with a mane of black hair and wearing some strange armor. He floats up to the farmer and comments on his low power level of 5. The farmer shoots Raditz with his rifle but the alien flicks the bullet back at the farmer. His scouter then senses a powerful being and he starts flying towards Piccolo. After talking for awhile, Piccolo gets annoyed at Raditz and fires a strong blast at him. When the smoke clears, he is shocked to see that he is unscathed. When the alien is about to attack Piccolo, he senses an even higher power level and flies off to Goku.

Goku has taken his son Gohan with him to visit Kamesennin, Oolong, Krillin, and Bulma, at the Kame House. After talking for a while, Goku suddenly senses an immensely powerful force. Raditz lands on the island and tells Goku a little about his Saiya-jin origin. He is a member of a strong warrior race that used to inhabit Planet Vegeta until it was destroyed. His real name is Kakaroto (or Kakarot) and he was sent to Earth as a baby in order to prepare it for sale on the market. Krillin does not sense the enormous power of Raditz and gets smacked in the face by the Saiyan�s tail when he tries to escort him off the island. Raditz then explains about the power of a Saiyan�s tail and his ability to transform as a result of having one. He then asks Goku to consider joining him in the conquest and annihilation of more planets, including Earth. Goku refuses and Raditz decides that he will take Gohan instead. Raditz gives Goku a quick knee to the stomach and he is down in pain. He then flies off with Gohan in his hand, saying that he will give him back only if Goku kills 100 humans by the next day.

As the gang decide what to do, Piccolo arrives and agrees to team up with Goku in order to take down Raditz. They fly off together with the Dragonball radar in hope of locating Gohan. Meanwhile, Raditz shuts the crying Gohan in his spacepod. His scouter suddenly flashes to a power level of around 710. He is shocked that its coming from the pod but later dismisses it as a result of a malfunctioning scouterpiece. Goku and Piccolo then arrive and Raditz realizes that his scouter was not broken. The two remove their weighted clothing and experience slight increases in their power levels. Raditz comments that its still no match for his own and the fight begins. Raditz displays blinding speed as gets the best of Goku and Piccolo in every encounter. The powerful Saiyan later fires two powerful energy blasts, one of which vaporizes Piccolo�s left arm.

After recovering a little from his injured arm, Piccolo begins to gather the energy for his new technique, the Makankosappo. Meanwhile, Goku has to keep Raditz busy so he can have enough time to concentrate on the move. Piccolo eventually fires it but Raditz dodges it. He then beats up Goku and has his foot on Goku�s stomach when Gohan bursts out of the spacepod and lands on the ground. He is obviously angry that his father had been beaten up badly and powers up. He flies in blazing speed with a red aura toward Raditz and headbutts him in the stomach. Raditz soon recovered from the painful attack and started powering up a blast that would kill Gohan. At the last moment, however, Goku manages to hold Raditz in a bear hug. Piccolo charges up his second Makankosappo and shoots it at the two. It pierces through their stomachs and kills both of them.

Later, Piccolo tells the others that he must train Gohan because of the power that he displayed earlier against Raditz. He takes off with the boy and proceeds to convert him from a spoiled brat to a brave and independent fighter. Piccolo makes Gohan go through some survival training and later returns to begin the actual training. By living together for almost a year, Piccolo and Gohan developed a symbiotic relationship with each other that made Piccolo less evil. At the same time, Yamcha, Tien, Krillin, and Chaozu trained at Kami�s Skypalace. In one episode, they were transported back to the past and brought to a planet where some fighting had just ended and skeletons littered the area. They go around searching for Saiyans to fights when they are discovered by two weak Saiyans. When they dispose of Chaozu, Tien starts attacking the two and is outmatched in speed and strength. Yamcha uses his Sokidan but the two Saiyans are unharmed when the smoke clears. They soon take care of Krillin and then Yamcha and Tien when all four are transported back to Skypalace.

Goku is traveling on Snake Way and arrives on Kaiosama�s planet after about half a year. There, he experiences the harsh training of trying to catch Bubbles and hitting Gregory with a mallet under the force of gravity that is ten times that of Earth. He eventually learns the Kaio-ken technique and how to form a Genkidama. As he races back towards Earth, Vegeta and Nappa have already arrived and quickly send a part of a city to the next dimension. They fly off to the two highest power levels, Piccolo and Gohan. Tien, Chaozu, and Yamcha later arrive also. Nappa grows some plant-like creatures called Saibamen in the ground and they start attacking the Z Team. Tien disposes of one and Yamcha seems to have the upper hand on them also. At the last moment, however, he locks onto Yamcha�s body and blows itself up, killing Yamcha. Krillin gets angry and fires an enormous blast at the Saibamen and the two Saiyans. Although the Saibamen were killed, Nappa and Vegeta were unharmed.

Nappa then started fighting the others all at once and was responsible for the death of Chaozu and Tien. Piccolo died as a result of saving Gohan from a strong blast from Nappa. This meant that Kamisama also died and that the Earth dragonballs are now useless. Goku finally arrives and easily beats up Nappa, who can�t believe that Kakarot is indeed a third-class Saiyan. When he flies towards Gohan and Krillin in an attempt to kill them, Goku uses Kaio-ken for the first time on Earth and beats up Nappa badly. He throws him to Vegeta, who sends his partner to the next dimension. The fight between Goku and Vegeta begins as Krillin and Gohan head back to Kame House.

Goku tests Vegeta out only to find that he is much more powerful than he expected. Knowing this, he powers up using Kaio-ken and attacks Vegeta. After a brief exchange of blows, it still isn�t enough to take down Vegeta. Vegeta powers up and releases an enormous explosion in the surrounding area. When the smoke clears, he rushes towards Goku and hits him with several blows. Goku recovers and uses Kaio-ken X2 to escape a fireball headed for him. The second fireball, however, barely misses him. He realizes that he must power up to Kaio-ken X3 and does so in spite of Kaiosama�s warnings. His power level rises rapidly as he exceeds Vegeta�s power level. Goku quickly overpowers Vegeta beats the Saiyan prince up so badly that a frustrated Vegeta later decides to blow up the Earth with his Gallic Gun.

As he powers up, Goku goes back to Kaio-ken X3 and prepares a super Kamehameha. The two blasts clash and a fireball battle begins. The two seem to be at equal power until Goku powers up to Kaio-ken X4. With that, Vegeta�s Gallic Gun is overpowered and he is sent flying towards the heavens. Although things seem to be settling down (Yajirobe even comes out to praise Goku for his display of power and speed), Vegeta manages to get off Goku's blast. His face is twisted with anger and he decides to transform to beat Kakarot. Goku is totally exhausted and looks helplessly as Vegeta lands back on Earth. He creates a bright ball of energy and throws it at the sky. It explodes and releases many Brute Waves that help Vegeta transform into his Oozaru form. In his gigantic Saiyan Gorilla form, he pounds Goku repeatedly.

Goku suddenly comes up with a plan and uses the Taiyo-ken technique to blind Vegeta so he can fly off and create a Genkidama at a safe distance. Before he can throw the ball, however, Vegeta sends off an enormous red blast that hits Goku and knocks the Genkidama out of his hand. He then proceeds to crush Kakarot�s bones and grinds him with both hands. Gohan and Krillin sense that Goku�s ki has decreased substantially and hurry back to save him. Gohan tricks Vegeta into looking at his direction while Krillin prepares a Kienzan behind his back in order to cut off his tail. It fails, however, and Goku is crushed. At the last moment, Yajirobe arrives and slices off his tail with his sword. Vegeta turns back to normal and is angry at whoever cut his tail off.

Although he is weakened, Krillin and Gohan still seem no match for him. With Goku�s encouragement, Gohan powers up and fights Vegeta while Goku successfully transfers the failed Genkidama to Krillin. He eventually throws it at Vegeta and it sends him again towards the heaven. He returns again and starts beating up Yajirobe and Krillin when he sees Gohan�s tail. Gohan looks at the white ball of energy that is still in the sky and transforms into Oozaru form. He crushes Vegeta before he turns back to normal.