Literature on natural immunity to tetanus is scarce. We examined antitetanus antibody levels with the enzyme-linked immunosorbent assay in 200 people living in an isolated community and clarified the influence of age and sex on immunity. In 197 subjects, antitoxin antibodies were measured. No sex differences were noted, and 30% had protective levels (above 0.01 IU/ml). The percentage of those considered protected was age dependent.