Forty patients of chronic renal failure (CRF) and five patients of acute on chronic renal failure (ACRF) were evaluated clinically and electrophysiologically for involvement of muscles. EMG studies showed features suggestive of denervation myopathy in 10 of patients of CRF only. Histopathological study of muscle biopsies, done in 25 patients with CRF, showed constellation of histopathological features suggestive of denervation myopathy in 48 and toxic myopathy in 24. In five patients with ACRF,denervation myopathy was observed in 60 and toxic myopathy in 20 cases on histopathological examination.