The drinking behavior of 4 male and 4 female subadult pigtailed monkeys (Macaca nemestrina), housed in 1 room, was studied during 3 phases. During phase 1 (10 days) cold orange juice was continuously available; during phase 2 (39 days) 10% alcohol (vol/vol) in cold orange juice; phase 3 (10 days) was a repetition of phase 1. Water was available throughout the experiment. Sex differences were evident. The males and females tended to drink in separate groups. The males drank mostly during the day, the females during the night. The females drank more than the males. In both groups the animals in the intermediate dominance positions drank the most alcohol. Animals who drank the most orange juice during phase 1 also drank the most alcohol during phase 2. The amount of orange juice consumed combined with dominance position accounted for a large amount of variability in the amount of alcohol consumed. On both a daily and hourly basis the animals tended to drink in binges.