Abstract: Details are given of a standard manner of recording breeding data of large mammals by game department officers, which is considered a great improvement on previous casual reporting. Information on the breeding in Northern Rhodesia of several ungulates and large Carnivora is summarised, and comparisons made with published data from other territories. It is stressed that much more study is needed, but certain points emerge from consideration of present information. Many species have their young at any time of year, and only a few have a really sharply defined birth season. The wart hog (Phacochoerus aethiopicus) seems markedly seasonal in the south of its range, but not in the northern parts. There is at present no data on the fluctuations in frequency of births among non-seasonal breeders. In the seasonally breeding species the actual birth months vary somewhat from north to south, and in the wildebeest (Connochaetes taurinus) there may be variation in the calving time due apparently to purely localdifferences of environment. The wild dog (Lycaon pictus) appears to be monoestrus, but data on the larger felids, though incomplete, seems to indicate that young may be born at any time of the year. Limiting factors in the study of breeding in African large mammals are pointed out, but it is suggested that further work on the lines of that carried out in Northern. Rhodesia would be profitable.