Abstract: Aegean Region standard cotton varieties and some commercial varieties were evaluated at four environments. Varietyxenvironment interactions was found significant for lint yield and lint percentage. The stability parameters, regression coefficient and mean squares of deviation from regression coefficient were computed and the relations between regression coefficients and lint yield and lint percentage were figured. The standard variety, Nazilli 84 S was the most stabile variety for lint yield, while Carmen, Ozbek 142 S and Sahin 2000 were group of the mid-adaptation to all environments. Ozbek 142 S also was a group of the best adaptation to all environments because of its regression coefficient and the highest lint percentage.