Postmortem storage under refrigeration (+2 °C) for 7 days of thesemimembranosus muscles from sheep, hare and roe deer and of the breast and leg muscles from chicken and duck did not result in a significant decrease of the total activities of the mitochondrial enzymes citrate synthase andβ-hydroxyacyl-CoA-dehydrogenase but caused a loss of the activity of lipoamide dehydrogenase (except in chicken muscle). During storage of the muscle tissue, there was no detectable release of the three enzymes from the mitochondria into the sarcoplasmic fluid except in venison at the point of spoilage. Therefore, storage of muscle under our conditions does not result in notable damage of the inner membrane of the mitochondrion.