This study evaluates the effects of different application rates of the plant growth regulator Atonik on yield, and fiber quality of cotton under irrigated, near optimal growing conditions. The study was conducted at the Texas A&M University Agricultural Research and Extension Center in Corpus Christi, TX, during 2001. Treatments included four rates of Atonik: 2.5, 5.0, 10, and 20 oz./ac applied at 9 nodes above white flower. Results from this study show that Atonik is also effective when used on high- yielding cotton. Atonik applied at 5.0 oz./acre at early bloom stage increased lint yield 256 lbs./acre (16.4%) over the untreated control (1557 lbs./acre). This yield increase resulted from a significant increase in individual boll weight. Fiber quality was not affected by Atonik applied at rates between 2.5 and 20 oz./ac. These results indicate that the use of Atonik may become an important tool to increase yields and profitability of irrigated cotton crops. More research in needed to confirm these results and further evaluate application rates and timing of application in both irrigated and dryland cotton.