This work deals with the influence of measurement accuracy of pitting areas on worm wheels on the formulation of empirical correlation between pitting, load and the number of load cycles. Since the analysis of pitting by means of an experiment is based on the determination of damaged areas, measurement errors have direct influence on the validity of such correlations. It is shown that measurement methods used in referent works concerning pitting of worm gears could result in significant and unpredictable variations of measurement results. The experimental part of the work included the monitoring of pitting formation on worm wheels made of AlSn6 and CuSn12 subjected to loads for 5⋅106 cycles. In both cases the worm gear was made of 16MnCr5. A visual difference between the areas affected by pitting and the rest of teeth surfaces has been taken as a criterion for the isolation of damaged areas. Based on the concept of machine vision, a methodology for acquiring and processing digital photographs has been defined in order to automate the procedure. Effects of the method on the measurement accuracy have been discussed as well. An analytical model for the determination of approximate tooth area is proposed for worm wheels having a ratio of b2H/b2R less than 1. The testing of model validity is conducted by a comparison against a 3D CAD model. Analyses of results indicate that the interaction between the sliding wear and pitting is a primary cause of non-uniform changes of areas damaged by pitting when the number of cycles is increased. The investigated case is classified according to this result and the ratio of the influence of sliding wear and pitting into a group of transmissions with smaller axis distances. A comparison between the extent and location of pitting damages among teeth has been conducted in order to identify a possible regular pattern. Analytical formulation of the extent of areas damaged by pitting depending on the load and the number of load cycles has been given together with the efficiency data for small extents of damaged areas and different sliding speeds.