The effect of potassium (K) fertilization rate (0, 30, 60,  90, 120 and 150 lb K2O/acre) and cotton cultivar on seedcotton yield, cotton petiole and soil-test K concentrations were evaluated in a 3-year field experiment. Potassium fertilizer treatments were applied to the same plots each year. Seedcotton yields, petiole K concentrations, and soil-test K were not affected (P =0.05) by cultivar or the cultivar by annual K rate interaction in any of the years. Potassium fertilization significantly affected the seedcottonyield only in the second and third year of the study.