The characteristic facies, joint contractures, muscular hypotonia, and growth and developmental delay of the Marden-Walker syndrome were present in a 19-month-old boy. Extensive evaluation of the neuromuscular system failed to identify a specific abnormality. Electromyography was normal with low amplitude. Light and electron microscopy of a skeletal muscle biopsy was normal. Histochemical study of this biopsy material was also normal. The pathogenesis of the syndrome is discussed.