On 13 September 1987, a severe radiation accident occurred in the city of Goiânia in central Brazil. Approximately 250 people were directly affected by the radiation, receiving slight to very severe external, partial or whole body, irradiation, and presenting internal and external contamination. Fourteen patients developed some degree of marrow failure, eight developed the clinical signs and symptoms of acute radiation syndrome (ARS), and four eventually died of ARS complications. Twenty-eight people showed acute localized radiation injuries ranging from first to third degree. The author describes the circumstances of the event, the first-aid measures taken on the site, and the medical structure organized to triage and treat the casualties. Aspects relating to hospital contamination control, radiation protection and decontamination procedures are also discussed.