Colon cancer is known to be heritable in humans, but the opportunity to investigate the genetic epidemiology of cancer in nonhuman primates has been limited by the size of available populations. The cotton-top tamarin (Saguinus oedipus) colony at the Oak Ridge Associated Universities (ORAU) Marmoset Research Center is a large population with a high rate of spontaneous colon cancer that has been monitored over several years, thus allowing investigation of the genetic basis for colon cancer in this colony. The presence of colon cancer at death was scored in 392 necropsies at the colony. Genealogical and demographic data for these animals were obtained from colony records. The heritability of the liability to colon cancer was estimated using maximum-likelihood-based pedigree analyses after evaluating the effects of gender, origin (wild-born or laboratory-born), and age at death on cancer experience. Cancer rates were not significantly different between males and females or between wild- and laboratory-born animals. Differences in age at death were also statistically insignificant for both laboratory- and wild-born animals. The heritability estimate for the liability to contract colon cancer is 17% for the ORAU cotton-top tamarins. This heritability estimate is not significantly different from zero, indicating no evidence for heritable variation in cancer experience in this population. If genetic factors affect cotton-top tamarin colon cancer, they are fixed or nearly fixed in this population.