A method for mixture formation for mixture-compressing internal combustion engines having a turbocharger and a fuel supply system for performing the method. The fuel supply system serves to regulate the fuel-air mixture in accordance with operating parameters of the engine and includes a first fuel supply element disposed upstream of a throttle valve and a second fuel supply element disposed upstream of a compressor. Below the operating temperature of the engine, fuel is fed only via the first fuel supply element. Above the operating temperature of the engine, the feeding of fuel is effected via the first fuel supply element until such time as the charging range begins, at a predetermined intake manifold pressure (p.sub.um), and above this pressure only via the second fuel supply element. The transition from one fuel supply element to the other takes place in accordance with a predetermined timed function. As a result, good fuel preparation and good cylinder filling are attained.