Using four concentrations of monocalcic phosphate solution in soil samples from five different soil series taken from the region of Piracicaba, State of São Paulo, Brasil, a study on phosphorus fixation was carried out. Of the soils used, three are Latosols (Soils I, II and V) whereas the rest (Soils III and IV), Podzolics. Is was observed a 200 hours incubation period for all treatments (P1 = 500; P2 = 1,000 and P3 = 1,500 P ppm). Each experimental unity consisted of a container with 10g of soil which received 4 ml of the mentioned solution. At the end of the trial, the evaluation of phosphorus content was done with an extractable solution of 0.025 N H2SO4 é and 0.05 N HCl. In order to make corrections on original data each soil sample received a 4 ml. destilled water treatment (P0) submitted or not to the 200 hour incubation period. The quantity of fixed phosphorus was calculated by subtracting the values found for P1, P2 and P3 those submitted to the 200 hour incubation period from the values for the "corrected strata", those not submitted to the incubation period.