The invention relates to a cylinder head (1) of an internal combustion engine, comprising at least one hollow camshaft (2) which forms an exhaust for blow-by gases containing oil mist from the crank housing and is also embodied as an oil mist pre fractionator for the preliminary separation of the oil part from these gases. Furthermore, an oil mist post-fractionator (5) is axially arranged on the end of the camshaft (2), in order to carry out an especially effective separation of oil dissolved in the blow-by gases.