The effects of different doses of the mepiquat chloride (MC) applied at different growth stages tand different does on the yield, yield components and fiber characteristics of cotton (G. hirsutum L.) were investigated under Amik Plain conditions under 1996 and 1997. MC treatments reduced plant height and improved earliness of cotton crop in both years while its effect on seed cotton yield showed inconsistency between years. It was also determined that multiple applications of MC had more positive effects on seed cotton yield and earliness. MC also affected significantly the seed cotton weight per boll in both years and the ginning outturn in 1996, MC did not create significant differences on the other morphological and fiber characteristics in both years.