Results aro presented of 14 cassava (Manihol -utilissima Pohl) fertilizer experiments, conducted in four regions of the State of São Paulo, varying in soil types. Ammonium Sulphate, Superphosphate of Lime, Bone Meal and Potassium Chloride were applied separately or mixed at the rate of 80 kg of Nitrogen, 120 kg of Phosphoric acid and 60 kg of Potassium oxide to the hectare. The fertilizers were applied in advance of planting in the planting furrows at 10 cm depth. The results can be summarized as follows: a) Ammonium Sulphate applied to lhe planting furrows caused rather poor sprouting of the cuttings; b) The influence of N, P, K fertilizers, separately or mixed varied according to soil type; in rather poor soil (Glacial and terra roxa cansada), P fertilizers increased root production; in better Salmourão soil, N fertilizer alone or mixed with P gave good results; in other regions either no beneficial effects of fertilizer application was noticed or a slight effect of N or N + K recorded. Due to high prices of fertilizers and to the relatively low value of cassava roots, the beneficial effects obtained in some of the regions are usually not considered to be of economic interest to the farmer.