The effect of fetal decapitation on the compositional and metabolic characteristics of the biceps femoris muscle of the pig was studied. Fetuses were decapitated at 45 days of gestation and sampled at 110 days of gestation. Muscle wet weight was greater and total dry matter was lower in decapitated (D) than in control (C) fetuses. Total muscle triglyceride content was not influenced by decapitation, but the triglyceride concentration was lower in D when compared to C fetuses. Muscle cell number (total muscle DNA) was not influenced by decapitation, but protein/DNA was greater in the muscle of D than C fetuses. Aerobic metabolism, as measured by oxidation of pyruvate, isoleucine, and palmitate to CO₂, was not influenced by decapitation. The rate of palmitate esterified and the ratio of palmitate oxidized/esterified was normal in decapitated fetuses. While the tricarboxylic acid cycle appeared to function normally, pentose shunt activity was higher in the decapitated fetal muscle than in control muscle. Although the rate of decarboxylation of leucine was lower in the muscle of D than in C fetuses, the net rate of leucine transaminated was similar between C and D fetuses.