Abstract: Effect of various levels of potassium on the yield of sunflower (Helianthus annuus L.) was studied at the Agronomy Research Area, Gomal University, D.I. Khan, during autumn 1997. The highest 1000-seed weight (53.71 g) was obtained from the plot, fertilized with 150kg potassium ha–1, while the minimum 1000-seed weight (46.41 g) was obtained in common plots. the highest seed yield (4153 kg ha–1) was also obtained in plots where 150 kg potassium per hectare was applied. The lowest seed yield was recorded in control plots (3402 kg ha–1). It can be suggested from these results that potassium. can be applied up to 150 kg ha–1 to obtain high seed yield of sunflower and to maintain the fertility regarding potassium I in the soil of D.I. Khan.