The development of the root system of two rice varieties, Iguape Agulha and IAC-435, planted either by direct sowing in rows or by seedling was studied in soils of the series «Barro de Telha» and «Coruputuba» under irrigation and drainage systems during the years 1967/68 and 1968/69. Individual plants of the variety Iguape-Agulha planted by direct sowing in rows produced 71.5 g of roots; 86% of the root weight were concentrated in the first 15 cm of the soil. When planted by seedling the root system weighed 40.3 g, 86% of which were concentrated in the upper 15 cm of the soil. The root system reached the depth of 55 cm. The variety IAC-435 planted by direct sowing in rows yielded 109.7 g of roots, 86% of which were found in the first 15 cm of the soil. When planted by seedling it weighed 69.8 g, 81% of which were concentrated in the upper 15 cm of the soil. The maximum depth reached by these roots was 75 cm.