The day time periods of activity ofGazella dorcas dorcasL. in the Sudan are 06.00–10.00 and 14.00–18.00 hr in winter; 05.00–08.00 and 16.00–18.00 hr in summer when day temperatures may exceed 45° C. The main types of activity are described and observations made on periodicity in other types of behaviour viz: defaecation, chewing the cud, standing, lying, drinking, feeding, playing and courtship. These are all related to ambient temperature, time of day and season of year.