We describe a neonate with hypotonia, weakness, early death owing to respiratory failure, and a severe form of arthrogryposis multiplex congenita. Postmortem studies revealed numerous ragged-red fibers and central nervous system abnormalities consistent with a mitochondrial disease. No NADH:ubiquinone-1 oxidoreductase (complex I) activity could be detected in skeletal muscle. These findings suggest that mitochondrial cytopathies can be associated with arthrogryposis multiplex congenita and should therefore be sought in neonates presenting with severe arthrogryposis.