An attempt was made to determine the effect of liming and phosphorus and potassium fertilization on the following fiber properties: length, length uniformity, fineness and strength. Data were collected from a permanent cotton yield trial carried out by Seção de Algodão, Instituto Agronômico, Campinas, on a soil grouped as latossolic B "terra roxa", série chapadão, at the Experimental Station of Campinas, during 1961-62 to 1963-64. The soil chemical analysis, previously run in experimental land, indicated very acid and low fertility conditions. It was concluded that: Liming reduced Micronaire index, without changing length, length uniformity and fiber strength. Phosphorus fertilization caused an increase in fiber length. Potassium fertilization caused an increase in length uniformity and Micronaire index.