This study was carried out at Ras Sudr Experimental Station, South Sinai during 2001 and 2002 seasons. Four sudan grass varieties (Giza2, Piper, Hybrid102 and Is3214) were tested under five nitrogen fertilizer (Mineral and biofertilizer) treatments under two levels of irrigation water salinity (3700 and 9200 ppm). Growth characters i.e. plant height, number of tillers/plant, stem diameter, number of leaves/plant, leaf area, leaves/stem ratio, and forage yield (fresh and dry weight of stem+sheaths and fresh and dry weight of forage yield) were recorded. In addition, carbohydrates, protein, fibers and ash percentages (in leaves and stems) and proline in leaves were determined. Results demonstrate that the Piper variety had the highest value of forage yield compared with the other varieties. The recommended dose of mineral nitrogen fertilizer gave the highest values followed by mixture of biofertilizers (Azospirillum plus Azotobacter) under the two salinity levels of irrigation water at both cuts (the first one was harvested after 65 days from sowing date and the second was obtained at the same time interval). Moreover there was a significant decrease in all growth characteristics and the yield of four sudan grass varieties by increasing the level of irrigation water salinity from 3700 to 9200 ppm except proline in leaves which significantly increased by increasing the level of salinity