Abstract: This study was conducted to determine the effect of time of nitrogen application on the growth, yield and quality of four forage sorghum cultivars included Abusabien (Sorghum bicolor L. Moench), Sudangrass (Sorghum sudanense) and two sorghum-Sudangrass hybrids (Panar and Speedfeed). Nitrogen was applied at the rate of 80 Kg N/ha with four application regimes: (N1) Control, (N2) application of the whole dose two weeks after sowing, (N3) application of the whole dose five weeks after sowing, (N4) application of 40 Kg N ha two G1 weeks after sowing + application of 40 Kg N ha five weeks after sowing. Parameters studied included: Plant G1 density, plant height, number of leaves per plant, stem diameter and leaf area (LA). In addition Dry matter yield, crude protein and crude fiber contents were studied. The results showed significant differences among the cultivars for most of the studied characters while no significant differences were detected among the fertilizer treatments. In most of the counts Abusabien was superior to other cultivars in plant height, stem diameter and LA of the first crop while other cultivars were superior to Abusabien in the dry matter yield of the ratoon crop. No significant differences were detected among the cultivars in the crude protein content. The effect of time of nitrogen application was not significant on most of the growth attributes and forage yield, but early application of the whole dose seemed to increase most of the growth parameters and forage yield. Nitrogen timing significantly affected the crude protein and crude fiber contents.