In order to study transfer of organic sulfur compounds in crude oil from fish flesh to animals, following experiments were conducted. Crude oil was administered orally to rat and distribution of organic sulfur compounds were determined by gaschromatography (with FPD). 1) Organic sulfur compounds remained after 24 hours administration. 2) Minute concentration of organic sulfur compounds in blood were detected 3 and 6 hours after administration. 3) Higher concentration of organic sulfur compounds among tissue tested was observed in liver 3 hours after administration and minute concentration was remained 6 hours after administration.