AbstractThe Primate Research Institute (PRI) dedicated a colony of 81 proven breeders (60 females, 21 males) to the National Chimpanzee Breeding and Research Program (NCBRP). When possible, infants were left with their mothers for a minimum of 18 months. Programs to define and reduce fetal wastage and neonatal mortality were implemented. Pregnancies were diagnosed both by RIA for serum chorionic gonadotropin and by ultrasound prior to day 30 of pregnancy. Of 65 pregnancies detected by ultrasound and RIA, 15 (23%) resulted in fetal loss. Without the use of ultrasound and RIA, only 8 of these losses would have been detected. Infant mortality (7 of 53 live births; 13%) was primarily due to maternal abuse or problems related to premature delivery. The incidence of losses due to maternal abuse has been reduced by placing females in single cages 2 weeks prior to their estimated delivery date so endangered infants can be recognized and removed. The new system provided the first opportunity for most of the mothers to care for their infants; 25 succeeded (in 2 instances in the second pregnancy only) and 12 did not (infants from 2 mothers were removed due to delivery of twins). During this 26‐month period the colony grew by 46 infants (58%), half of which will be retained as future breeders. Thus, the NCBRP goal of achieving a self‐sustaining population appears via