Twenty-one species of rodents were trapped or observed in two forests in the Panama Canal Zone. Data on the ecology, molt, and food habits of seven species are presented. Among the terrestrial rats and mice, three species (Liomys adspersus, Oryzomys capito, and Proechimys semispinosus) were common in the Pacific slope forest, whereas two (Oryzomys capito and Proechimys semispinosus) were common in the Atlantic slope forest. Year-round breeding occurs in eight of nine species; Liomys adspersus breeds seasonally. Adults of L. adspersus and P. semispinosus molt during restricted portions of the year, but there was no apparent synchrony of molt in adults of Heteromys desmarestianus, Oryzomys capito, Zygodontomys microtinus, and Sigmodon hispidus. Ecological segregation serves to minimize competition among the rodents in both forests.