Irregular fluctuations of friction coefficient around the mean value were analysed by means of fractal geometry methods. Particular data were recorded during the steady-state stage of dry sliding tests carried out in Si 3 N 4 ball – on – Si 3 N 4 /SiC nanocomposite disc configuration. It was proven that the set of points {sliding distance (time), friction coefficient}, considered as a geometric object in a two-dimensional space, has the property of a fractal curve. The fractal dimension of this curve increased with increasing wear rate gained in a particular wear test. This could indicate a possible correlation between the wear rate and the fractal dimension of friction coefficient as a function of sliding distance (time).