The REINZ company relies on a twenty year experience in the development and high volume production of cylinder head gaskets for aluminum engines. Basic requirements which these gaskets are to comply with are discussed. Above ail. thermal expansions of components resulting from the decisively different thermal coefficients of steel and aluminum are of special importance in terms of technology and design.It is described which structural aids will serve to obtain the distribution of sealing pressure which service calls for. Reasons are discussed which have led to the structural design of cylinder head gaskets for those engines which are built today on the base of Reynolds 390-Alloy.