Methyl, ethyl and butyl acrylate were hydrolyzed to acrylic acid in rat liver, kidney and lung homogenates. The rates of hydrolysis of the various esters in these in vitro studies were comparable; hydrolysis rates were approximately 20 times higher in liver homogenates than in kidney or lung homogenates. The esters also disappeared rapidly when added to blood in vitro. However, the disappearance in blood was not associated with the appearance of acrylic acid. Ethyl acrylate was found to react spontaneously with GSH in vitro and this reaction was catalyzed greatly by enzymes in 100 000 x g liver supernatant. Acrylic acid did not react with GSH in vitro. Ethyl acrylate, but not acrylic acid, depletes non-protein sulfhydryls when added to blood in vitro. Thus, the disappearance of acrylate esters in blood in vitro could be due at least in part to binding with non-protein sulfhydryls in red blood cells rather than to hydrolysis.