White suckers (Catostomus commersoni) accumulated the PCB Aroclor® 1232 and dieldrin from water at approximately the same rate. However, they accumulated higher PCB levels than dieldrin levels when exposed to equivalent concentrations of these substances. The uptake pattern of Aroclor 1232 components on a whole fish basis and in gill and intestinal tissue was similar to Aroclor 1232 components to which the fish were exposed. The presence of additional components having short chromatographic retention times was observed in liver, brain, and kidney tissues in fish exposed only to Aroclor 1232.