Overall evidence from epidemiologic studies in the workplace suggests that dioxin is a human carcinogen, but whether low doses affect the general population remains to be determined. The authors examined the spatial distribution of soft-tissue sarcomas and non-Hodgkin's lymphomas around a French municipal solid waste incinerator with high emission levels of dioxin (16.3 ng international toxic equivalency factor/m3). Not consistently associated with dioxin exposure,-Hodgkin's disease served as the control cancer category. Clusters were identified from 1980 to 1995 in the area ("département') of Doubs by applying a spatial scan statistic to 26 electoral wards. The most likely and highly significant clusters found were identical for soft-tissue sarcomas and non-Hodgkin's lymphomas and included the area around the municipal solid waste incinerator; standardized incidence ratios were 1.44 (observed number of cases = 45, focused test p value = 0.004) and 1.27 (observed number of cases = 286, focused test p value = 0.00003), respectively. Conversely, Hodgkin's disease exhibited no specific spatial distribution. Confounding by socioeconomic status, urbanization, or patterns of medical referral seemed unlikely to explain the clusters. Although consistent, these findings should be confirmed by further investigation (e.g., a case-control study in which dioxins are measured in biologic tissues) before clusters of soft-tissue sarcoma and non-Hodgkin's lymphoma are ascribed to dioxin released by the municipal solid waste incinerator.