Five lectins were used as fluorescence microscopic markers for sugar residues in skeletal muscle. Biopsy specimens were taken from patients with X-linked muscular dystrophy (Duchenne's and Becker's), patients with other neuromuscular diseases, and normal controls. In both the controls and the pathologic samples, concanavalin A gave a bright fluorescence of the myofiber surface, whereas soybean agglutinin and Dolichos biflorus agglutinin fluorescence was negative. Peanut agglutinin and wheat germ agglutinin were more avidly bound to the sarcolemma and/or endomysial connective tissue in the patients with X-linked muscular dystrophy than in the controls or the patients with other conditions. The altered saccharide pattern may reflect either a myofiber membrane change or a specific mesenchymal reaction in the dystrophic muscle.