Cotton producers faced with the loss of arsenic acid as a harvest-aid compound must be informed of other lowcost and effective compounds. Cacodylic acid is one alternative for producers. Field studies were conducted in 1990 and 1991 on irrigated picker cotton grown in the Brazos River Bottoms to evaluate the performance of cacodylic acid used alone or in combination with other harvest-aid compounds. In 1990, cacodylic acid (1.5 and 3.0 pt/A) performed as well as or better than Def (1.5 pt/A) used alone. Cacadylic acid also tended to increase the defoliation of Paraquat (1 pt/A), Def (1.5 pt/A), and Dropp (0.1 lb/A) over that of either product used alone. In 1991, a heavy thunderstorm resulting in over two inches of rain in a brief period began six hours after the application of the defoliation treatments. The rainfall lowered the performance of Dropp, but had little if any effect on the performance of cacodylic acid, Def, and Prep. Cacodylic acid when used alone at rates equal to or below 1 pt/A was inferior to the 2.0 pt/A rate. Defoliation from cacodylic acid at the 2.0 pt/A rate did not differ from that of Def (1.5 pt/A) used alone. Cacodylic acid did improve the performance of Dropp; however, because of the rainfall, Dropp (0.1 lb/A) was not commercially acceptable. Defoliation rates of the Def combinations did not statistically exceed those of Def used alone. A rate of cacodylic acid of 1.5 to 2.0 pt/A appears to be necessary to achieve defoliation rates comparable to Def used alone across both years. The addition of cacodylic acid to Def appeared to give more consistent defoliation across years than Def used alone.