ABSTRACT. In 22 patients with sarcoidosis, symptoms and signs of muscle involvement were scanty, but muscle biopsy showed epithelioid cell granulomas consistent with sarcoidosis in 11 patients (50%). Serial sectioning of the muscle biopsies increased the diagnostic yield. The incidence of muscle involvement was highest among patients with both acute sarcoidosis and erythema nodosum. Involvement of other organs was common in patients with muscle sarcoidosis. In two patients with negative scalene node biopsy and negative bronchial and trans-bronchial biopsies, muscle biopsy showed histological evidence of sarcoidosis. Muscle involvement is common in patients with sarcoidosis, but in many cases there are few or no symptoms. In patients with both acute sarcoidosis and erythema nodosum, muscle biopsy frequently provides histological evidence of the disease. Good cooperation with the pathologist and serial sectioning of the biopsies are necessary if muscle biopsy is to be used as a routine in the diagnosis of sarcoidosis.