The toxicity variations of puffer fishes toxin on species, sex, organs seasons and sea area collecting subjects were observed in 615. subjects of 15 species during 1978-1981. The remarkable differences of toxicity were found by species and/or by subjects. Takifugu pardalis, Takifugu poecilonotus and Takifugu niphobles, which are habitually eaten in Japan, had a strong toxicity and some of them were strongly toxic in the muscle. It was indicated that female puffer fishes have a higher toxicity than the male. In particular, the toxicity from genital organs was significantly higher in the female puffer fishes than in male. No difference no sex was observed in the skin. Compared with the toxicities on the collecting sea areas, Inland sea of Seto and Japan sea, the mean of toxicity and the incidence rate of toxic subjects collected in Japan sea were higher than those of in Inland Sea of Seto i.e. The difference was observed by the living sea environment of puffer fishes. The wild Takifugu rubripes was obviously more toxic than the cultured. It was suggested that the variations between the wild and cultured puffer fishes should be due to the difference of the metabolism for the production and accumulation of tetrodotoxin which would be influenced by the foods and the closed environment.