Abstract: This study was conducted in Aegean Region, western Turkey, in non-infected and naturally infected fields to determine the influence of verticillium wilt on yield and fiber quality parameters. The cotton cultivars, Nazilli 84 S (Aegean Region standard cotton cultivar), Carmen (tolerant to verticillium wilt) and Cukurova 1518 (susceptible to verticillium wilt) were used as a material. It was found that verticillium wilt significantly reduced the seed cotton yield, fiber length and fiber strength. Yield reduction was determined as 15.93%. Finally, Carmen was recommended for yield and fiber quality in infected area.