23 potential carriers of Duchenne muscular dystrophy (DMD) and 20 of their apparently healthy brothers were studied for evidence of any subclinical form of the disease. The results of the study confirmed that it was possible to confirm the diagnosis of a ‘high genetic risk’ carrier by integrating the results of clinical studies, estimation of basal serum CPK, steroid-CPK test, EMG and ECG observations. Similarly, the subclinical state of DMD could also be detected with certainty in 10% of the brothers of DMD carriers. The results may be applied for genetic counselling to bring down the incidence of the disease in the commun