The influence of lubricant characteristics and operating parameters on the EHL in hypoid gears was studied. The full thermal elastohydrodynamic analysis of lubrication was applied, based on the simultaneous solution of the Reynolds, elasticity, energy, and Laplace's equations. Using a computer algorithm, the influence of oil viscosity, pressure-viscosity and temperature-viscosity exponents, supplied oil temperature, speed and minimum oil film thickness on maximum oil film pressure and temperature, EHD load carrying capacity, and power losses in the oil film was studied. The calculated EHL characteristics depended on the method by which the pressure viscosity relation was described. The use of thicker oils was with positive effects on EHL load carrying capacity of the oil film, but in the field of higher viscosities, this effect mostly diminished. The pressure viscosity exponent had a very strong effect on the maximum oil temperature, and the temperature viscosity exponent on the maximum oil pressure and EHD load carrying capacity. By the increase in speed and by the reduction of minimum oil film thickness, the load carrying capacity was considerably improved. This is an abstract of a paper presented at the World Tribology Congress III (Washington, DC 9/12-16/2005).