The extractable total activities of lipoamide dehydrogenase (LIPDH), citrate synthase (CS), andβ-hydroxyacyl-CoA-dehydrogenase (HADH) were determined in different muscles (longissimus dorsi, semimembranosus, diaphragma) from cattle and pigs, and in the breast and leg muscles from chicken and ducks. The subcellular distribution of these enzymes was elucidated by determination of the enzyme activities in the pressjuice of the intact muscle tissue. In the muscles of the different species positive correlations between myoglobin content and the activities of the three enzymes were found, which were closer for pigs and chicken than for cattle and ducks. At least 90 percent of the total activity of LIPDH, CS and HADH was located in the mitochondria.