Salinity is a major threat to summer forage crops in Egypt. Thus, two experiments were performed at lysimeter experiment area at Soil Improvement and Conservation Res. Dep., during the two successive summer seasons 2018 and 2019 in Sakha Agricultural Research Station Farm, Kafr El-Sheikh Governorate, Egypt, to study the effect of irrigation water salinity on forage and seed yield of fodder cowpea and some soil properties. The experiments were designed as a split plot with three replicates. The main plots were occupied by three irrigation water salinity levels: normal salinity of irrigation water S1 (EC=0.65; dS m-1 416 ppm), S2 (EC=2; dS m-1 1280 ppm), S3 (EC=3.5; dS m-1 2240 ppm). Sub plots were occupied by three cowpea genotypes, namely Sakha 5 (V1), Sakha 7 (V2) and Balady (V3). The data showed that the highest value for fresh yield (2.80-2.82 kg. plot-1) and dry yield (0.602 - 0.610 kg. plot-1) was obtained with applying irrigation water salinity level S1. In addition, the genotype Sakha 5 gave the highest values for fresh and dry forage yields. The highest values for plant height, stem diameter, number of branches and leaf stem percent were recorded under S1 comparing with the other two levels. With respect to genotype, Sakha 5, it gave the highest values for plant height, number of branches and leaf stem ratio. But, Balady gave the highest value of stem diameter in the two seasons. The data showed that the highest values for number of pods/plant, number of seeds/pod, 100- seed weight and seed yield were also recorded under normal water irrigation (S1) comparing with the two salinity levels. The genotype Sakha 5 gave the highest value for number of pods plant, number of seeds pod, 100- seed weight and seed yield. It was observed that seed yield was decreased by 11.32 and 24.75% under water salinity levels of S2 and S3, respectively in relation to irrigation with fresh water (S1).