This study reports concentrations of tributyltin in seafood collected from eight sites around the world and assesses potential human health risks. Samples of fish, crustaceans, cephalopods (i.e., squid), and bivalve molluscs were purchased from markets in two Asian cities, one Australian city, three European cities, and two North American cities. Samples were then analyzed for tributyltin, and the chemical concentrations observed were used to calculate potential human health risks from consumption of market-bought seafood. TBT residues in marketable seafood were consistent worldwide, averaging 185 ng/g dry weight. For different reasons, pelagic fish and bivalve molluscs tended to have slightly higher residues than squid, demersal fish (sole/flounder) and crustacea. TBT concentrations in seafood from France and Korea were at least twice as high as those from the other countries. Based on average per capita seafood consumption rates for each country, the amounts of TBT ingested did not exceed proposed thresholds for chronic effects, suggesting negligible risks to the average consumer.