We studied a 2-year-old child with congenital hypotonia and proximal muscle weakness. There was no family history of neuromuscular disease. The child also had hypospadia. The central nervous system was apparently not involved. Muscle biopsy showed a dystrophic pattern and dystrophin was absent as shown by immunofluorescence and by Western blot. Vinculin and spectrin were also reduced, while merosin was normal in muscle fibers. This observation suggests that congenital hypotonia may be associated with a severe form of dystrophinopathy.