This study was designed to evaluate the response of Australian cotton (Fiber Max 819) to chemical defoliation. The field experiment was established on April 13, 1999, at southwest of San Pedro, Coahuila, Mexico. The experimental design was a randomized complete block with four replications. Nineteen treatments of defoliation were evaluated and compared with a control without defoliant application. Defoliant evaluation was based on a scale of 0 to 100 (0 meaning no defoliation). Number of bolls and open bolls, dry weight of abscised leaves, seedcotton (kg/ha), yield components, and fiber quality were measured. Butifos, ethephon with cyclanilide alone or with adjuvant and thidiazuron with adjuvant or ethephon and cyclanilide were the best treatments to defoliate Fiber Max cotton variety. Defoliation treatments produced negative effects on seedcotton.