This experiment aims at evaluating the influence of N-P-K fertilization on wheat yield in a soil previously limed. This study was carried out in the wheat producing area, in the southern part of the State of São Paulo. There were used two levels for nitrogen. O and 60 kg per hectare four levels for phosphorus, 0, 80, 160 and 240 kg per hectare, and two levels for potassium, 0 and 35 kg per hectare. The statistical analysis demonstrates signiticant differences at 1% level for the treatments. The reaction to phosphorus was remarkable, and it raised the yield up to 730% in the treatment 030, as compared with the control plot. The analysis for the proteic nitrogenous materials showed the positive effect of nitrogen in the absence of phosphorus. In this case, the increase in protein was 5.5%.