An outbreak of puffer fish poisoning in a family with four cases of which one was fatal is reported. The outbreak occurred in July 1998 in Nosy Be, an island located at the north-western part of Madagascar. Diagnostic investigation with application of the mouse bioassay suggested poisoning with a tetrodotoxin as the etiology. The amount of the toxin was 16 MU (mouse unit) per gram meal. A continuing surveillance of the seafood intoxications either in the country or in the west Indian Ocean region is needed.