This paper examines the distribution of non-offspring nursing or ‘allosuckling’ in warthogs Phacochoerus africanus. Of the 16 breeding groups studied, 11 contained two or more nursing females. Allosuckling occurred in six of these groups (55%). The number of juveniles per nursing female was lower for groups with allosuckling, although juvenile mortality was not measurably affected by either allosuckling, group size or the number of females in a group. Time spent drinking was longer for juveniles in smaller litters but was not influenced by allosuckling or juvenile age. Longer intervals between the females' nursing bouts resulted in longer drinking bouts for the juveniles, but there was no correlation with inter-meal intervals. The proportion of successful sucking bouts increased with juvenile age. This success rate was greater in groups without allosuckling, suggesting a better co-ordination between mother and offspring. Females appeared able to distinguish between juveniles and to nurse selectively. Four- to 5-year-old females nursed fewer juveniles than did older or younger females in their groups and were thus less likely to be donors.