The association between dermatomyositis and polyradiculoneuritis is rarely citated in the speciality literature. Our patient had at first a disorder that looked like dermatomyositis, then she associated polyradiculoneuritis. At the presentation to our hospital the two diseases were combined, being very difficult to differentiate. The discrimination between these two had been made by performing a muscular biopsy and EMG studies. This emphasizes once again their importance in defining the muscular impairment from the neurogenic one.