In response to the prescribed demand for a modern fighter aircraft, Castoldi submitted a proposal for an aircraft based upon his 1935 design studies. On 24 December 1937, the first prototype (MM.336) C.200 conducted its maiden flight at Lonate Pozzolo, Varese, with Macchi Chief Test Pilot Giuseppe Burei at the controls. Officials within the ministry and Macchi's design team fought over the retention of the characteristic hump used to enhance cockpit visibility; after a protracted argument, the feature was ultimately retained.