Effects of different water level on yield and yield components of the drip irrigated cotton were evaluated in Amik Plain in the East Mediterranean Region of Turkey. Four levels of irrigation water were tested in2003 and 2004. Treatments were 25 (I25), 50 (I50), 75% (I75) of the full irrigation treatment (I100) which received 100% class-A pan evaporation. Numbers of irrigation events were 5 and 8 in 2003 and 2004, respectively. Under I25, I50 and I75 treatment conditions, evapotranspiration, total cotton seed yield, boll weight, lint percentage, number of sympodial branches and leaf area index decreased while some boll parameters such as boll weights and opened boll numbers increased. Increase of boll number per plant under water stress condition showed that cotton had high ability for adapting water stress conditions. The highest yield was obtained in the I100 treatment. A second degree polynomial relation could adequately describe the cotton seed yield response to the irrigation water amount. The highestirrigation water use efficiency (IWUE) was obtained with the I50 treatment
