The social organization and behaviour of 35 individually recognizable territorial male Antarctic Fur seals (Arctocephalus guzellu), were studied during the breeding season at South Georgia. Adults of both sexes remain at sea throughout the winter. Among the first bulls ashore were those which had the longest territorial tenures. The mean period of tenure for 13 bulls seen to copulate was 34.3±9.0 days. New bulls continued to arrive and fight for territories on the breeding beach throughout the study period. Many were successful and mean territory size declined from about 60 m2 in mid‐November to 22 m3 in December. More than 3000 boundary displays between known bulls were recorded and analysed. These were largely ritualized although in 14% of displays bites were exchanged. Outright fighting was infrequent in relation to the total number of inter‐male encounters. 94% of of the fights occurred on the first day a pair of bulls became neighbours. Less than 50% of bulls holding territory were seen to copulate and the mean copulation frequency for these bulls was 10. During late December, by which time most females had mated, adult males ceased to maintain their territories actively and many abandoned them completely. Features of the social organization are compared with those of other otariid seals and the interrelationships between period of tenure, territory size, form of boundary display and copulation frequency are discussed in relation to environmental and social influences. Within fur seals and sea lions, differences in social organization during the breeding season do not seem to be related to phylogenetic differences.