Adult monkeys caught in the wild were housed in 2 harems and used for breeding during 7 successive years. Monkeys born in captivity and reared in the parental groups or in peer groups were also used for breeding. The live birth production rate amounted to 80% and reproduction was stable over the 7 year period. All but one of the females born in captivity showed normal maternal behaviour towards their firstborn infants. Aggression between females, breech deliveries, infanticide and reluctance of the male to copulate with females which grew up in his harem, were significant factors that reduced productivity.