A canine model was used to test the hypothesis that critical intracompartmental pressure leading to ischemic muscle necrosis is linked to diastolic blood pressure. Twenty adult dogs were subjected to an infusion of autologous plasma into the anterolateral muscle compartment of the left hindlimb to create an elevation in compartment pressure. There were four experimental groups of five dogs each. In group I, the compartment pressure (CP) was maintained at the animals' diastolic blood pressure (DBP); in group II, at 10 mm Hg less than the DBP; in group III, at 20 mm Hg less than the DBP; and in group IV, at 30 mm Hg. The pressure was measured continuously in the proximal, central, and distal segments of the compartment during an 8-hour period. Immediately postoperatively, and, on the first, fourth, seventh, and fourteenth days one animal from each group was killed. The tibialis cranialis muscle was then removed and analyzed using light and electron microscopy. The critical pressure threshold for ischemic muscle necrosis was found to be 20 mm Hg less than the diastolic blood pressure.