4 cases with an identical neuromuscular disorder are presented. The disorder was characterized by slowly progressive weakness and wasting of the proximal muscles together with either ocular or bulbar symptoms, fatigability, positive tensilon test, myasthenic response on repetitive nerve stimulations, elevated serum creatine phosphokinase, and neuropathic and myopathic muscle pathology. All the patients showed a fairly good response to anti-ChE medications and steroid administration. Serum creatine phosphokinase levels returned to normal values after steroid therapy. Myasthenia, polymyositis or other neuromuscular disorders were discussed in the differential diagnosis.