Seventy-nine pediatric patients with neuromuscular diseases were examined for dental and occlusal characteristics. Fifty-six patients suffered from primary muscle disease (myopathies) including 43 with Duchenne's muscular dystrophy. The neuromuscular disorders in 19 patients were of neuropathic origin, while four were caused by a fault in the neuromuscular junction. Posterior crossbites occurred more often in the myopathies (57%) as compared with the neurogenic dystrophies (14%) (P less than 0.003). Although not statistically significant, the prevalence of open bite was also higher in the combined myopathies (21%) as compared with neurogenic disorders (9%). The Duchenne patients exhibited a statistically significant delay in dental emergence (1.06 years), unlike the other myopathies (0.31 years) and the neurogenic disorders groups (-0.03 years). This study emphasizes the influence of muscular environment on dental development in general. The dentition may be more affected in muscular dystrophies stemming from degenerative or inflammatory muscle damage than in those originating from nerve malfunction or disorder of the neuromuscular junction.