A technique that proved itself satisfactory for determining the sand particle size distribution in certain soils and for its numerical and graphical representation is described. Samples from soils of the two most important sedimentary rocks of the state of São Paulo, "arenito Bauru" and "arenito Botucatu" were used, as well as soil samples from the "São Carlos" and "Santana" plateaus. A preliminary test was carried out to determine the minimum sieving period necessary for a satisfactory separation. Periods of 10, 20, and 30 minutes were compared and gave nearly the same results. For further determinations a 15 minute sieving period was used. The sand particle size distribution of the "arenito de Botucatu" samples was more uniform and had a narrower range than the others. The distribution range of the samples widened in the following order: "Santana", "São Carlos", and "arenito de Bauru". The last sample had a more uniform size distribution than the other two. Fractions coarser than the mode predominated in the samples from "Santana" and from "São Carlos"; particles finer than the mode predominated in the "arenito de Bauru"; the fractions coarser and finer than the mode were about equal in the "arenito de Botucatu".