This was mainly for two reasons : the He-112 was a very complex machine to build, particularly because of its advanced but extremely difficult to build wings, and, furthermore it was a very expensive aircraft. Clearly these were serious disadvantages for a plane supposed to be enter mass-production ( and quickly ! ) so the Bf-109 was chosen as the new main fighter of the Luftwaffe. A small batch of He-112A's was still ordered to see if something could be done in time to improve the design and to be used for demonstration flights at air shows, hoping to obtain orders from other countries. In 1936, the plane was improved, creating the B version. It had a new, completely redesigned fuselage, a new vertical stabilizer and a fully-enclosed cockpit. Several more powerplants were tested, such as the DB600A, DB601 and the Junkers Jumo 211Ga. The DB-600 powered He-112 was actually 20 km/h faster than the Bf-109B but the RLM saw no reason to put two roughly similar designs into production. The He-112B2 settled with the Jumo 211Ga and  entered production in late 1936, whilst its three prototypes spent the second half of 1937 flying at air shows and touring Europe, in an effort to convince other air forces that the plane was worth its price ( the cost of a single He-112B was 163278 Reichmarks ). One of the prototypes even saw action with Condor Legion in Spain, where the cannon-armed He-112B performed well as ground-attack aircraft. Several nations expressed interest, namely Japan, Austria, Finland, Hungary, and, the very last one, Romania. Romania had realized by 1938 that war was inevitable, so a delegation was sent to the traditional aircraft suppliers to purchase any modern planes available. After several unsuccessful attempts, when they arrived in Germany, they were offered the excellent Bf-109, but there was a catch : deliveries could begin only after production exceeded Luftwaffe needs. Since this was a remote possibility, the ARR had to settle for 30 Heinkel He-112B's that could be purchased right away.
	It was late April 1939, that a group of Romanian pilots arrived at Heinkel works for conversion training and instruction. Transition from their PZL P-11's and P-24E's to the significantly more advanced He-112B1's and B2's was slow, but ended in October 1939. When pilots finished their training, they simply returned home with their new aircraft. One plane was lost in Germany during training, and one was slightly damaged on the way to Romania, but was repaired at SET works. A single additional He-112B was delivered in 1940 to replace the one lost.

Once the first He-112B arrived, it was tested against the prototype of the Romanian IAR-80 fighter, but after the IAR-80 demonstrated it was superior in most aspects, no further orders for He-112's were placed and the IAR-80 was immediately ordered into production instead.

After the last He-112 was delivered, two fighter squadrons ( the 51st and the 52nd ) were equipped with it and tasked with defending Romania's capital from enemy air attacks. After tensions between Romania and Hungary started to escalate, the 51st squadron was deployed inside Transilvania. One of its He-112's was the very first Romanian plane to shoot down an enemy aircraft in WW2, when on the 27th of August 1940, Lt. Nicolae Polizu of the 51st squadron shot down a Hungarian Caproni Ca-135bis biplane.

At the start of operation Barbarossa, 24 He-112's were in service and ready for action. On the 22nd of June 1941, 12 He-112's escorted the Po-633 light bombers of the 2nd Bomber Group sent to bomb the Soviet airfields at Bolgrad and Bulgãrica. At Bulgãrica, about 30 Russian I-16 were waiting for them, and a furious air battle began. Second lieutenant Teodor Moscu got three I-16's , but was himself hit and barely made it to a friendly airfield ( click here for the full story ), whilst three bombers were shot down by enemy AA artillery and fighters. The He-112's were employed mostly for ground-attack and airfield strafing missions for the rest of the Bassarabian campaign, with good results. A typical combat day would start at dawn with a few strafing runs on Soviet airfields, followed by "search and destroy" missions behind enemy lines, paying special attention to trains and artillery positions. Constant action resulted in serious "wear and tear", which slowly reduced the number of available He-112's. On the 13th of August, all remaining planes were given to the 51st Fighter Squadron, bringing it to full strenght. Fifteen aircraft took part in the siege of Odessa and performed coastal patrols over the Black Sea afterwards, without seeing much action during this period. Reports generally complained about the He-112 having poor speed, due to the fact that by now it was clearly an underpowered plane.

A line of He-112B's on the east front

Technical data of the Heinkel He-112B