Abstract: A field experiment was conducted to compare the response of sunflower cultivar SF-187 to muriate and sulphate of potash, each at 0,50, 100 and 150 kg ha-1. Different sources and levels of K did not significantly affect the plant height, stem diameter, 1000-achene weight and harvest index. However, leaf area per plant, stalk yield, number of achene head-1, seed yield and oil contents were affected significantly by K2O levels. A significant increase in seed yield and oil contents was observed upto 100 kg ha-1 but both these parameters were decreased beyond this limit. A decrease of 26 and 20 per cent in seed yield was noted by potassium application at the rate of 150 kg ha-1 in the form of sulphate of potash and muriate of potash respectively. The application of potash more than 100 kg ha-1 seems to be uneconomical to sunflower in Faisalabad conditions.