Washing processes, detergant agents, washing cycles and temperatures can often cause damage on fabrics. The aim of this work was to determine chemical and physical changes on cotton fabrics with different washing conditions. A Box-Bhenken statistical design was used to evaluate the effect of washing temperature (40 -50-60 degrees C), number of washing (10, 30, 50) and washing agent (only water, base detergent, detergent with bleaching agent) on the average degree of polymerization. The effect of multiple washes on cotton fabrics was evaluated by means of average polymerization degree, tensile strength, whiteness index and scanning electron microscopy. Whiteness index decreased significantly using with base detergent and bleaching agent containing detergent, whereas washing with only water did not affect significantly to whiteness index, with increasing number of washing. However, temperature (p > 0.05) individually were not found statistically significant for whiteness index. As number of washing and temperature increased, tensile strength values decreased. Also, washing agent (p > 0.05) individually were not found statistically significant for tensile strength. When evaluated in terms of average polymerization degree values, after the washings with base detergent and bleaching agent containing detergent, there is a greater decrease in the average polymerization degree relative to the only water washings. While the temperature increased in washing process, the average polymerization degree decreased and the lowest average polymerization degree was obtained at 60 degrees C and 50 washing cycles SEM images indicate that number of washing and the content of detergent are important parameters in the washing process. The worst image in this study was obtained with 50 washes using detergent containing bleaching agent. Washing processes cause undesirable results on the surface of fabrics.