The prevalence of dental fluorosis in a nonfluoridated area was determined and related to the reported fluoride ingestion histories of the children examined. A convenience sample of 543 schoolchildren in rural areas of Michigan was examined for fluorosis using the Tooth Surface Index of Fluorosis. Questionnaires that asked about previous use of fluorides were sent to parents of all children examined. The response rate was 76 percent (412 usable questionnaires). A criterion for inclusion in the data analysis stipulated that only fluorosed surfaces that occurred bilaterally would be included. Fluorosis was found on 7 percent of all tooth surfaces and only in the mild form. Twenty-two percent of the subjects were classified as having fluorosis. Dietary supplement was the only fluoride that was found to be significantly related to the occurrence of fluorosis. A greater proportion of the subjects with fluorosis listed physicians, rather than dentists, as the source of fluoride prescriptions. The results demonstrate similarities to the fluorosis reported in other studies in nonfluoridated areas, but also suggest the need to minimize the occurrence of fluorosis through proper assessment of a child's fluoride exposure and the judicious use of additional fluoride.