The homogenized tissue samples of puffer fish were extracted with boiling 0.1% acetic acid solution for 2 times, then the combined filtrate was defatted with ether ethyl for 2 times and the water phase were diluted with 0.05 mol/L PBS for ELISA determination (adjusted pH to 6.5-7.0). The results showed that the minimum detecable concentration of tetrodotoxin was 1.0 x 10(-3) mg/L (0.1 ng/assay), and the standard curve was linear between 1.0 x 10(-2) and 1.0 mg/L. The recovery rates from tetrodotoxin spiked samples of this method were 73.8%-117.4%. The accuracy of ELISA was compared with the traditional mouse bioassay system. The results showed no significant differences between the two methods (for paired-t test, P > 0.2), and significant correlations in tetrodotoxin concentration were obtained (r = 0.916).