Effects of N, P and K on yields of cotton were investigated using data obtained over an 18-year period from a factorial experiment comparing various combinations of the three nutrients. The results clearly indicated a significant and fairly consistent response of cotton to the application of fertilizer nitrogen, but the rate of increase in yield with increased N gradually diminished. The response to P was erratic and to K was negligible. The response to N did not vary with levels of P or K. Whether lack of response to P on the alkaline soils of the Gezira was due to sufficient already available in the soil, or because the added fertilizer was fixed and rendered unavailable to the plant needs further investigation. Lack of response to added K was attributed to the high content of available K already in the Gezira soil.