We report a retrospective study of the clinical signs and symptoms associated with a point-source outbreak of fish poisoning that occurred with a fish captured from the Arafura Sea, northern Australia. Twenty cases (16 Aboriginal and 4 non-Aboriginal) characteristic of ciguatera, including 4 inpatients and 16 outpatients from the Gove Hospital, were identified based on the pattern of clinical symptoms and signs after ingestion of a large coral cod from a known ciguatera-prone coral reef. In the absence of a serologic test for the victim, laboratory analysis of a 230-g sample of the coral cod (Cephalopolis miniatus), using both mouse bioassay and HPLC/mass spectometry, showed that Pacific ciguatoxin-1 was the principal toxin involved. Intravenous mannitol was administered to one patient without clear benefit. Risk factors for ciguatera poisoning are ingestion of larger portions of reef fish from ciguatera-prone areas. Despite apparent local awareness of the distribution and etiology of the disease, large common-source outbreaks of ciguatera still occur.