A cylinder head cover for an internal combustion engine includes an oil separator with a vortex chamber extending in a longitudinal direction from a proximal end to a distal end. Said vortex chamber comprises an essentially pipe-shaped wall extending in said longitudinal direction, a gas inlet arranged at said proximal end of said vortex chamber and oriented tangentially to said essentially pipe-shaped wall, for tangentially blowing blow-by gas into said vortex chamber, such that a gas vortex flow helically rotating along said essentially pipe-shaped wall in the longitudinal direction from said proximal end to said distal end of said vortex chamber is created, and a gas outlet opening. The gas outlet opening is arranged in the region of said distal end of said vortex chamber.