Effects of fertilizers mixtures with or without sulfur on cotton earliness and some characteristics of fiber and bolls, obtained in a field experiment carried out at Guaira County (SP) in a oxisoil -"Latossolo Roxo" - during the years of 1974/75 to 1977/78, are related. The following conclusions can be drawn from the results: a - soil fertilizations with concentrated superphosphate or ordinary superphosphate resulted in early picking of cotton crop. Plant cycle, was delayed with split application of ammonium sulphate; b - both concentrated superphosphate and ordinary superphosphate increased significantly boll weight and fiber length, but only ordinary superphosphate gave significant increases on seed weights and Micronaire values; c - length uniformity, maturity, strength and percentage of fiber were not influenced by these treatments.