This paper deals with the dependence of needle penetration of petroleum waxes on structure and content of the crystalline fraction as well as the viscosity of the amorphous fraction. The crystallinity is defined as the relation of the total crystallization enthalpy of the respective wax to the ideal crystallization enthalpy of the n-alkane that is equivalent to the average C atom number of the wax. The viscosity of the amorphous phase is defined by the viscosity of the molten wax at 100 C. It is shown that both parameters have a decisive influence on the needle penetration-temperature behavior of waxes. The complete cross-linking of the crystal lattice is of great significance for the properties. Influences of wax composition on crystallinity and viscosity are discussed.