In order to correlate lipoprotein and apolipoprotein profiles with atherosclerotic lesions at autopsy, the feasibility of using postmortem serum in these determinations was evaluated. Lipoprotein and apolipoprotein profiles in dogs and monkeys were compared in pre- and postmortem serum samples, and it was found that, up to 24 h postmortem, no appreciable differences were observed in apolipoprotein A-I, B, E, and A-IV serum concentration when compared to premortem values. Electrophoretic mobilities and apolipoprotein gradient gel immunoblotting also revealed no differences in apolipoprotein size distribution. We conclude that postmortem sampling up to 24 h can be used effectively to approximate premortem lipoprotein and apolipoprotein profiles provided that careful sampling techniques are observed.