Dose-death time curves in ddY strain male mice were established for paralytic shellfish poison (PSP) components: saxitoxin (STX), neoSTX, gonyautoxin 5 (GTX5), a mixture of GTX1 and GTX4, a mixture of GTX2 and GTX3, and a mixture of protogonyautoxin 1 (PX1) and PX2. Their curves clearly differed from the curve for STX derived from Sommer's Table. Logarithm of toxicity in mouse units (MU) of these toxin components and reciprocal of death time (sec) of mouse correlated well with each other, irrespective of PSP component. Regression lines for STX, neoSTX, GTX5, a mixture of GTX1 and GTX4, and a mixture of GTX2 and GTX3, were statistically indifferent from each other (p>0.05), and were collectively expressed by an equation, Y=182X-0.220, in which Y represents the log of toxicity (MU) and X, the reciprocal of death time in sec. Thereby, toxicity (MU) would be calculated according to the following equation; MU=10(182/t)-0.220, in which t represents death time in sec. Partially purified scallop PSP consisting predominantly of GTX1-4 gave essentially the same regression line and its toxicity value would also be determined by the above equation.