On April 29, 1996, three cases of tetrodotoxin poisoning occurred among chefs in California who shared contaminated fugu (puffer fish) brought from Japan by a co-worker as a prepackaged, ready-to-eat product. The quantity eaten by each person was minimal, ranging from approximately 1/4 to 1 1/2 oz. Onset of symptoms began approximately 3-20 minutes after ingestion, and all three persons were transported by ambulance to a local emergency department (ED). This report summarizes the investigation of these cases by the San Diego Department of Environmental Health (SDEH) and the Food and Drug Administration (FDA).