This experiment was carried out to determine the optimum fertilizer level of N-P-K for maximum yield of grasses at hill-land pasture. The pasture species tested were orchardgrass, tall fescue, alfalfa and ladino clover. The results are summarized as follows: 1. The difference in yield of treatment 1, 2, and 4, 5 was significant at the 5% level. In other word, alfalfa yields from 6-30-30 kg/10a and 6-40-30 kg/10a (N-P-K) application were significantly increased over the yields from 4-20-20 kg/10a and 4-30-20 kg/10a (N-P-K). In observing the yield from the treatment 5 where 10 kilograms of phosphate was additionally applied over the treatment 4, it was increased in yield but failed to show statistical significance. With these results, the most optimum rates of N-P-K for alfalfa production are 6-30-30 kg/10a. 2. Ladino clover showed the highest yield at treatment 6 with statistic significance at the 1 percent level over the other treatments. Therefore, NPK rates of 6-30-40 kg/10a would be the most optimal rates for maximum production of ladino clover. 3. Orchard grass yield showed significance at the 1 percent level among other treatments except treatment 3 and 4. The highest yield was also shown at treatment 6 where NPK rates applied 40-30-40 kg/10a. 4. Tall fescue yield showed high significance at the 1 percent except treatments between 2 and 3, 5 and 6. The highest yield was observed at treatment 6 where NPK was applied 40-30-40 kilograms per 10a. 5. Nitrogen content of dry matter was 0.91-1.05% in 20 kg of N and 1.05-1.26% in 30-40 kg of N per 10a. The absorption rate of nitrogen applied was 23-31% regardless of the nitrogen level. Potash content of dry matter was increased in accordance with increasing K rates. 6. The gross income was the highest on the N-P-K application of 4-20-30 kg/10a in alfalfa and ladion clover, 40-30-40 kg/10a in orchardgrass and 30-20-20 kg/10a in tall fescus.