We exposed juvenile puffer fish, Takifugu obscurus(30 days after hatching) to various aqueous pollutants including 4 kinds of inorganic metals (Ag, Cd, Cu and Hg), 2 organotin compound.; (tributyltin ［TBT］ and triphenyltin［TPhT］) and 5 polycyclic aromatic hydrocarbon (PAH) compounds (chrysene, fluoranthene, naphthalene, phenanthrene and pyrene) to estimate median lethal concentrations (LC50s) of each pollutant after the 96-hour acute exposure. Among the inorganic metals, Hg (52 $mu extrm{g}$/L; 96-h LC50) was most toxic to test animals and followed by Ag (164 $mu extrm{g}$/L), Cu (440 $mu extrm{g}$/L) and Cd (1180 $mu extrm{g}$/L). Aqueous TBT was more toxic between the two organotins; the 96-h LC50 for TBT (5.1 $mu extrm{g}$/L) was 3 times lower than that of TPhT (17.3 $mu extrm{g}$/L). The acute toxicity of PAH compounds was highest for chrysene (1.5 $mu extrm{g}$/L; 96-h LC50) and decreased in the order of pyrene (65 $mu extrm{g}$/L) > fluoranthene (158 $mu extrm{g}$/L) > phenanthrene (432 $mu extrm{g}$/L) > naphthalene (8690 $mu extrm{g}$/L). The toxicity of PAH compounds wat closely related to their physico-chemical characteristics such as $K_{ow}$ and water solubility, and well explained by simple QSAR relationship. The sensitivity of puffer fish to various inorganic and organic pollutants was generally comparable to various fish species widely used as standard test species in previous studies and further evaluation should be conducted to develop adequate testing procedure for T. obscurus when used in various toxicity tests.