Effects of N and K applications on characteristics of cotton cultivated in latosolic soils, of the State of São Paulo, not deficient in potassium, are related with results of soil analysis. Potash application diminished plant precocity particularly in soils with medium K disponibility. This character was not influenced by N application. Nitrogen application increased the weight of bolls and seeds, and the fiber index, particularly in soils with higher K contents. These characteristics were not influenced by K application. In soils with higher K content, N application increased also the fiber length and Pressley index. The fiber characteristics were not affected by K application.