Environmental influences on reproduction in female giraffe were investigated by calculating conception dates for 123 calves and twenty foetal giraffe from the eastern Transvaal, South Africa. Of these, 60% occurred during the 4 months December to March. This period is the peak of the austral summer when plant leaf production is at a maximum, the preferred food species of the giraffe are abundant and the protein and energy content of these are high. Rainfall is also highest at this time.