Potential carriers [23] of Duchenne muscular dystrophy (DMD) and 20 of their apparently healthy brothers were studied for evidence of any subclinical form of the disease. It was possible to confirm the diagnosis of a high genetic risk carrier by integrating the results of clinical studies including the estimation of basal serum CPK [creatine phosphokinase] steroid-CPK test, EMG [electromyographic] and ECG [electrocardiographic] observations. The subclinical state of DMD was detected with certainty in 10% of the brothers of DMD carriers. The results may be applied for genetic counseling to bring down the incidence of the disease in the community.