Ambulation latencies of pair-reared 6-day-old male and female chicks were measured (i) in the presence of a cagemate; (ii) in the presence of an unfamiliar chick; (iii) in isolated chicks. Results showed that a) in animals tested with a cagemate there were no differences in ambulation latencies between males and females; b) in animals tested with an unfamiliar chick ambulation latencies were higher in females than in males; c) in animals tested in isolation ambulation latencies were higher in males than in females. It is suggested that gender effects in the open-field behaviour of young chicks might be due to a stronger social reinstatement motivation in females than in males.