A multistage compressor (1) for compressing gases has a low-pressure range (7) and a high-pressure range (4), the high-pressure range (4) including at least one reciprocating compressor (3) driven via a crankshaft (5) and the low-pressure range (7) including at least one screw compressor (20) provided as a low-pressure compressor (6) having a rotating displacer (8) coupled to the crankshaft (5) of the reciprocating compressor (3).