Two brothers with motor retardation since the first months of life presented waddling ataxic-gait with lumbar lordosis, joint contractures and generalized muscle weakness. Both presented altered cerebellar tests and scanning speech. Creatine kinase, electromyography (EMG) and muscle biopsy pointed to muscular disease while CT scanning and NMR imaging showed cerebellar vermis agenesis. On this evidence we diagnosed the unusual association of vermian agenesis and congenital muscular dystrophy.