Shot samples of the wild rabbit, Oryctolngus cuniculus (L.), were obtained during 1954 and 1955 from two sites in Kew South Wales representative of different climatic regions, and the reproductive organs were examined histologically. The reproductive pattern, as indicated by changes in the fertility and pregnancy rates in the does, and testis weights and percentage fertility in the bucks, was found to have a relation to environmental factors which indicate that the timetable of breeding was modified, if it was not very largely governed, by the incidence of rain and the response of the vegetation to it. Evidence of a considerable pre-natal loss of lit'ters was obtained; and this probably explains, in part, the often marked difference between the fertility and pregnancy rates that was noted at all times of reproductive activity except during the spring breeding peak. Outbreaks of myxomatosis occurred in both sites during the period of study. KO evidence was obtained to indicate that the fertility of recovered does was affected, but the fertility of bucks was reduced for a few months at least after recovery from the infection.