A great disadvantage of synthetic fibers is their low hydrophilicity. Polyester fibers are particularly hydrophobic. In the first place, this affects the processability of the fibers. The surfaces are not easily wetted, thus impeding the application of finishing compounds and coloring agents. In addition, a hydrophobic material hinders water from penetrating into the pores of fabric. An additional advantage is a decrease in build-up of electrostatic charge. Besides an improved processability of hydrophilic textiles, a number of advantages from the consumer's point of view are improved washability, as the water can remove hydrophobic stains more easily, and enhanced wearing comfort due to greater water absorbency. For these reasons, hydrophilicity of polyester fabrics was improved using Trametes versicolor. Incubation conditions were determined as; the polyester fabrics were incubated for 10 days at 28 degrees C and 175 rpm. The modification medium was contained 1 g/L glucose and pH of medium was 4. The modification degree was determined according to the contact angle measurements. Water retention values were compatible with contact angle values. FTIR and SEM images showed that the modification occurred on the PET fabric surface. More hydrophilic PET fabric was made by T. versicolor. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 690-695, 2011