Examinations of dental pathology in five genera of caviomorph rodents found caries and periodontal disease in both grazers and frugivores, although the prevalence differed between the two groups. Caries was more prevalent in the frugivores (10.5-19.8%) than in the grazers (1.1-8.7%); mild periodontal disease occurred occasionally in the grazers (5.6-8.7%), but was almost absent in the frugivores (0.0-1.3%). The consistent findings of caries and periodontal disease suggest that ecological differences between the two related groups, and the subsequent dietary differences, are important in determining the incidence of dental pathology.