Records of black rhinoceroses obtained from different areas of Kenya suggest a very close relationship between body weight and length and chest girth. The best regressions are: log weight on log length+log girth, and weight on length x girth2. The square of the correlation coefficient in both cases is more than 0.98, and the relations appear to be independent of habitat and sex. In contrast the two sexes show marked differences in the relation between front and back horn length with the males tending to grow relatively longer front horns. Attempts to predict the size of the animal and the length of its horns from the spoor were less successful.