To assess the effectiveness of i.v. Mannitol treatment for Ciguatera Poisoning, 35 patients were treated from the Miami-Caribbean area with symptoms of acute and chronic Ciguatera Poisoning. Information was collected on demographics, fish type and location, timing and type of symptoms, and response to treatment. Iv Mannitol (1 g/kg infused 3-4 hours) given within 48 hours dramatically decreased the acute morbidity of Ciguatera Poisoning without serious side effects. Treatment also appears to be safe and effective in chronic cases up to eight weeks from ingestion of toxic fish.