In order  to  study  the  effect of  nitrogen and potassium on yield and  yield  components on four bread wheat cultivars; Gemmiza 11, Sids 12, Sids 13 and  Shandaweel 1, the treatments included three levels of nitrogen: 50, 75 and 100 kg N/fad accompanied by tow levels of potassium: 24 and 48 kg Ko2/fed. Field experiment was conducted at Sakha Agricultural Research Station, Agricultural Research Center, during the two growing seasons of 2008 - 2009 and 2009-2010. The treatments were arranged in a spilt-spilt plot design with four replications. The main plots were devoted to nitrogen levels and the sub-plots were allocated to potassium levels, while the sub-sub plots were designed to cultivars. Increasing nitrogen levels up to 100 kg N/fad. Resulted in significant gradual increase in days to heading and maturity, plant height, number of spikes/^m2, number of kernels/spike, and grain yield/fad. On the hand, there was no significant effect for potassium fertilization levels on the tested agronomic characters.  The results indicated that Gemmiza 11 was the earliest in heading and maturity in the two seasons. Shandaweel 1 gave the highest grain yield/fed in the first season while it was the latest one in days to maturity.Sids12 cultivars gave more spikes/^m2in the both seasons.While,Sids 13cultivars gave the highest values of 1000-grain weight. The interaction between nitrogen and potassium, nitrogen and cultivars, potassium and cultivars and cultivars, nitrogen and potassium rates did not show any significant effect on grain, straw yield/fed and harvest index in the two seasons. However, the interaction between nitrogen rates and cultivars and potassium and cultivars was significant for number grains/spike in the two seasons. The interaction between nitrogen levels and cultivars was significant for no. of spikes/^m2 in the second season. Also, the interaction between nitrogen and potassium levels was significant for no. of spikes/^m2 in the first season.         It could be concluded that Shandaweel 1 can be cultivated under fertilization at 100kgN/fed to produce the highest yields of grains and straw per Fadden.