Gastrocnemius muscle specimens from 19 patients with varicose veins without clinical neuropathy were examined with a light microscope after staining fresh-frozen sections with modified Gomori trichrome and after histochemical reactions for NADH diaphorase, ATPases and phosphorylase. Only four muscle specimens from these 19 patients were regarded as completely normal. In five of the patients (26 per cent) a combination of fiber type grouping and small-group atrophy, and in nine patients (47 per cent) fiber type grouping with occasional small angulated fibers were observed. These changes were less frequent in nine biopsies from brain-death control patients (11 per cent). Various forms of abnormalities in the distribution of NADH diaphorase were seen in 13 patients with varicose veins (68 per cent) and in one of the controls (11 per cent). Necrosis and phagocytosis of the muscle fibers were present in three biopsies from patients with varicose veins (16 per cent) and in one of the controls (11 per cent).