In order to determine the optimum dietary protein and energy requirements of broiler chicks, 480 chicks of meat-breed (Maniker) were fed 12 kinds of diet formulated to contain the various level of dietary protein for starters (21, 23, 25%), for growers (18, 20, 22%), and for finishers (16, 18, 20%), respectively, and dietary energy (2800, 3000, 3200, 3400 ㎉ ME/㎏) according to 3 x 4 factorial design. The results of the present study were summarized as follows. 1. According to the results of starter periods. body weight gain and feed efficiency were considerably (p$lt;0.01) improved but feed intake was decreased as the levels of dietary energy increased. No difference was observed in the growth rate by the chicks fed the diet containing different level of dietary protein. Feed efficiency was significantly (p$lt;0.01) improved as the level of protein increased. 2. In the grower periods, the growth rate and feed conversion rate were improved as the levels of dietary protein and energy increased until an adequate level of protein was supplied, although no remarkable difference among the protein levels. Feed consumption was increased with decreasing levels of dietary protein and energy. 3. For finishing broiler chickens, dietary protein levels had some significant effects on body weight. Chicks receiving 20% protein had poorer body weight gain as compared with those receiving 1.8 or 16% protein levels. Feed consumption was increased as the level of dietary energy decreased. Feed conversion eras considerably (p$lt;0.01) improved as the level of dietary energy and protein increased. 4. According to the results of overall feeding trials from 0 to 9 weeks, total body weight gain from starters to finishers was increased with increasing level of energy. Total feed consumption was remarkably (p$lt;0.01) higher for the low energy group than for the high energy group. Overall feed conversion rate was improved as the level of dietary energy and protein increased. 5. There were no statistical differences in mortality of the experimental birds due to dietary treatment. 6. Feed cost per kilogram body weight gain of birds fed the diet of 23-20-18%-3000, 21-18-16%-3200, 21-18-16%-3000, and 21-18-16%-2800 ㎉ ME/㎏ groups was less than that of chicks fed other diets. Considering feed cost, body weight gain and feed efficiency, the best results were obtained at 23-20-18%-3200 ㎉ ME/㎏, 23-20-18%-3000 ㎉ ME/㎏, 21-18-16%-3200 ㎉ ME/㎏, and 21-18-16%-3000 ㎉ ME/㎏ groups. According to the above results, it could be concluded that a diet containing 23% protein and 3200 ㎉ ME/㎏ for starters, 20% protein and 3200 ㎉ ME/㎏ for growers, 16 to 18% protein and 3000 ㎉ ME/㎏ for finishers would be suitable for optimum performance.