In this study, for dry sliding wear of some polymers against stainless steel discs in a pad on disc tribotester, uncertainties of wear rate and coefficient of friction were calculated according to ISO "Guide to the Expression of Uncertainty in Measurement". In the uncertainty budget of wear rate, the uncertainty of the slope of the regression line which was fitted to the wear volume-sliding distance curve, was added. In addition, the uncertainly of taking moisture of polymer pins while weighing was determined, and it was added to the uncertainty budget. So an attempt is made to calculate proper uncertainty for experimental results. It was seen that the most important uncertainty contribution was the repeatability of experiments.