We investigated levels of the pollutant tributyltin (TBT) in blood of pufferfishes (six species), Japanese sea perch, red sea bream, Japanese common goby, Japanese flounder, rockfish, conger eel, and sea mullet collected off the coast of northern Kyushu, Japan. We found considerable levels of TBT (1.4–190 ng/mL) accumulated in the blood of these fish. Blood TBT concentrations were 1.3–22.5 times liver concentrations and 4.9–78 times muscle concentrations, except in conger eel and mullet. We detected TBT (16–111 ng/mL-blood) in the plasma of the fine-patterned puffer (Takifugu poecilonotus) year-round, without any apparent seasonal trend. These results suggest that fish inhabiting coastal areas of Kyushu, Japan, continue to be contaminated with TBT.