The Bloch MB-151 was the first production version of the MB-150 single seat fighter aircraft ordered by the French air force in 1938. In May 1938 work had started on producing 25 pre-production MB-150s, but it had quickly become clear that the MB-150 was not well suited to mass production, and so the entire fuselage was quickly redesigned to increase the speed of manufacture.
The new MB-151 used a Gnome & Rhône 14N11 engine, providing 910 hp. Other changes included a slightly reduced wing surface, the use of metal covered control surfaces and the replacement of the two 105 gallon fuel tanks in the wings of the MB-150 with one 109 gallon tank in the fuselage. The MB-151 was armed with two 20mm S9 cannon and two 7.5mm MAC 1935 machine guns, all mounted in the wings.
The first MB-151 flew in August 1938. The aircraft was never quite as fast as expected, and work very rapidly switched to the MB-152, which used more powerful engines. By May 1940, 140 Bloch 151s had been accepted by the French Air Force, but the majority of them were relegated to training units. Only 37 Bloch MB-151s were operational on 10 May 1940. It would be the MB-152 that would face the Luftwaffe in May and June 1940.