We report the outcome of trial of clenbuterol in four adult muscular dystrophy patients. One patient with Becker type, one with Miyoshi type, and two with facioscapulohumeral type were given clenbuterol (30 or 40 micrograms/day) for 6 to 18 months. We evaluated muscle strength of isometric contraction, grip and pinch power, compound muscle action potentials of intrinsic muscles, vital capacity, urinary creatinine excretion, and muscle CT. Power and volume of well preserved muscles increased mostly, while those of atrophic muscles did not improve. Vital capacity increased in two patients. No improvement of ADL was observed presumably because ADL was mainly determined by the most atrophic and weak muscles. Irrespective of type of muscular dystrophy, administration of clenbuterol may be beneficial in early stage of the disease.