The publication of a 1971 study from Japan on chronic methylmercury poisoning in adults provides an occasion to reexamine the history of Minamata disease and its social and political repercussions. Research findings were suppressed or held back due to controversies that were tearing the Japanese scientific community apart. Similar controversies occurred outside of Japan as well. Only now are the long-term adverse effects of environmental methylmercury exposure becoming clear. The delayed release of the 1971 results therefore reminds us as epidemiologists of our obligation, even in the presence of scientific uncertainty, to call attention to preventable risks.