After an accident in a chemical plant in Seveso, Italy, on July 10, 1976, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) spread over a populated area. The event was exceptional because children were also affected and because the contamination took place not only through direct exposure but also through inhalation and the ingestion of contaminated foods, especially fruits and vegetables. This paper illustrates the early dermatologic lesions, the late acneic (chloracne) lesions, and their evolution during a 10-year period. Peculiar cutaneous findings, histologic data, and a comparison with previously reported similar accidents are also included.