A method is presented for quantitatively determining triclocarban in blood. Triclocarban is extracted from blood with ether, isolated by TLC, and measured through its UV absorption at 265 nm in methanol. This method is sensitive to 250 ng (50 ppb in 5 ml of blood) of free triclocarban with a relative standard deviation of 5.2%, correlated with a radiotracer analysis of 14C-labeled triclocarban. It has been applied successfully to the analysis of triclocarban in human and rabbit blood.