The friction conditions in the mesh of worm gear drives have big influence on the efficiency of worm gears. Because the friction conditions of worm gears can't be determined directly@ a special test rig (three disk test rig) was built to simulate the contact conditions for discrete points along the contact lines of a worm gear. The highest values of the local coefficient of friction occur under poor lubricating conditions with the vector of the rolling speed in direction of the contact line@ normally in the center of a worm gear flank@ the lowest coefficients of friction in the area of the outlet. Furtheron the local coefficients of friction strongly depend on the type of lubricant and material combination and to a minor extent on load@ lubricant viscosity and oil temperature. The investigations at the three disk test rig offer a cost saving possibility to examine the different influences on the coefficient of friction of worm gears.