The caprellid amphipod Caprella danilevskii was exposed to five levels (0, 10, 100, 1000 and 10 000 ng l−1) of tributyltin (TBT) both in the embryonic stage (5 days) and over its whole life history from hatch to death (50 days) to examine the effects of TBT exposure on survival. In both experiments, survival rate decreased drastically as TBT concentrations increased, with a decrease occurring even at 10 ng l−1 in both short- and long-term exposure experiments. Significant differences were found in the survival rate between the control (no control specimens died) and the three concentration groups except 10 000 ng l−1 (all specimens died), regardless of sex. However, the survival rate in response to exposure to TBT has been found to be similar among all combinations of TBT concentration except 10 000 ng l−1, in both sexes. Furthermore, no significant differences were observed in the survival rate in response to exposure to each concentration of TBTCl between sexes. These findings suggest that the risk of survival in response to exposure to TBT between sexes is similar in the caprellids. No sex-specific differences of mortality by TBT exposure were observed in the species although feminization by TBT exposure was found in the caprellids in a previous study. These results all lead to the conclusion that TBT disturbs the mechanism of sex determination during the embryonic stage of the species.