A centrifugal precipitator having a housing and a rotatable driven rotor for precipitating oil mist from crankcase ventilation gas of an internal combustion engine. The housing has an inlet for gas to be deoiled, a deoiled gas outlet and an oil outlet. The housing includes a metallic main element surrounding the rotor and carrying the rotor bearing. A housing bottom is built onto the main element from below. The housing attaches with a flange to a counterflange or module of the engine. The housing flange is formed on the main element and the housing. The oil outlet runs through a first flange part of the housing bottom and this flange part has a circumferential rim. A second flange part of the main element has a collar engaging over part of its periphery behind the rim and can be clamped with the rim in between against the counterflange.