The proper amount of fertilizer application is the main factor affecting the grain yield and its components of durum wheat. Hence, the field experiment was carried out in the winter seasons of 2017/2018 and 2018/2019, at Research Farm of Faculty of Agriculture, Sohag University, to study the effects of potassium fertilizer levels (zero, 25, 50 and 75 kg K2O /fed.) on yield and its components of four durum wheat genotypes (Bani Suef 6, NGB 7214, NGB 5399 and NGB 4816). A randomized complete block design (RCBD) was used in split-plot with three replicates. The results showed that potassium fertilizer levels were significantly affected on all studied characters except plant height in the 1st and 2nd seasons, and harvest index in the 1st season only, as well as genotypes had significantly effect on yield and its components traits in both growing seasons. Bani Suef 6 and NGB 7214 genotypes produced the highest values of grain yield compared to other genotypes in both seasons. Moreover, NGB 7214 accession produced the maximum values of spike length (cm), No. of Spike /m2, No. of grain/spike, 1000-grain weight (g), biological yield (ton/fed.) and straw yield (ton/fed.) in the 1st and 2nd seasons, respectively. In general, the highest grain yield (20.27 and 19.70 ard./fed.) were obtained by Bani Suef 6 genotype when fertilized with 75 kg K2O /fed., and NGB 7214 genotype when fertilized with 50 kg K2O /fed. interaction treatments, respectively.