An experiment was conducted in laboratory and hapa, to observe the effect of 17 a-methyl testosterone on growth and sex-ratio of common carp, Cyprinus carpio var. communis (L.). Four treatments viz. Ti, T2, T3 and T4 having 0, 150, 200 and 250 mg 17 a-methyl testosterone respectively in per kg nursery feed Starter-I (SABINCo) were used for a period of 35 days in laboratory system. Then the hormone treated fish were again reared in experimental hapa and fed nursery feed Starter-III (SABINCo) for another 90 days for the maturation of their gonad. After termination of the experiment the sex of all the fish were identified with gonad squashing method to identify male, female and sterile Jishes. In terms of growth performances significantly higher (p<0.05) weight gain was found in T3 but there was rio significant variation in survival rate of C. carpio among the four treatments after 35 days of the experimentation. The highest percentage (74%) of male was observed in T3 compared to other treatments after 90 days of the experimentation. The results indicated that the oral adrninistration*of 17 a-methyl testosterone at the dose of 200 mg per kg feed could be effective for the masculinization and sterilization of common carp with higher growth.