A cross-sectional study of Campylobacter spp. infection was conducted on 125 infant (Macaca nemestrina and Macaca fascicularis) in an infant primate nursery housing infants from birth to 18 months of age, and 145 M. nemestrina aged from 4 months to 15 years at another facility (Primate Field Station) housing animals from birth to aged adults. The objective was to determine the prevalence of Campylobacter spp. in various age groups and to investigate the correlation with diarrhea. In the Infant Primate Research Laboratory approximately 70% of infants were infected at 18 months-old. Campylobacter coli was isolated from approximately two-thirds of the infected infants. One-third were Campylobacter jejuni and occasional infants were infected with a naladixic acid resistant, hippurate negative (NAR) Campylobacter spp. At the Primate Field Station virtually all animals cultured in 4-6 month-old, 16-20 month-old, and 3-5 year-old age groups were positive. Approximately one-third of middle-aged adults (10-15 years old) were positive with C. coli or NAR Campylobacter spp. Environmental factors such as location and movement of animals may provide an explanation for the prevalence data obtained in the two facilities and different age groups of animals. An etiologic role of Campylobacter spp. in diarrhea of laboratory primates was not established in this study.