Massive doses of methylprednisolone were given to dogs prior to severe, lethal, hemorrhagic shock. An untreated group of dogs subjected to hemorrhagic shock served as controls. No persistent significant differences were seen in cardiac output, mean arterial blood pressure, superior mesenteric artery flow, and survival. Calculated total peripheral resistance tended to be lower in the treated dogs and was significantly lower after reinfusion of shed blood. Pretreatment with methylprednisolone did not prevent plasma elevations of the lysosomal enzymes, cathepsin D and beta-glucuronidase. Stabilization of hepatic lysosomes in treated dogs subjected to hemorrhagic shock was not evident. The results failed to indicate significant salutary effects of methylprednisolone sodium succinate in this lethal hemorrhagic shock model.