To study the effects of different N fertilizer on berseem clover forage quality in an intercropping with basil, this experiment was conducted in Research Farm of College of Agriculture, University of Tehran in 2011. Experimental treatments were arranged as split plots based on a randomized complete block design with three replications. Different N fertilizers consisted of control (no N fertilizer), 100% chemical fertilizer, biological fertilizer, and integrated fertilizer (biological fertilizer + 50% N fertilizer) were assigned to the main plots while different additive intercropping patterns of basil sole cropping (weed free), basil sole cropping (weed contaminated), berseem clover sole cropping (weed free), berseem clover sole cropping (weed contaminated), berseem clover + 25% basil, berseem clover + 50% basil, berseem clover + 75% basil, berseem clover + 100% basil were assigned to the sub plots.  The results showed that the highest forage DMD (60.07%) and WSC (11.2%) were obtained from berseem clover + 100% basil when received biological fertilizer, and no fertilizer, respectively. The highest CP (30.1%) was observed in berseem clover + 50% basil when received integrated N fertilizer. The highest ash content (8.04%) was measured in berseem clover sole cropping (weed free) treatment when received 100% chemical fertilizer. The highest CF content was measured in berseem clover + 25% basil when received biological fertilizer. The highest berseem clover forage yield (in two harvests) (4833.33 kg/ha) was obtained from berseem clover sole cropping (weed free) treatment when received 100% chemical nitrogen fertilizer. The highest Land Equivalent Ratio (LER=1.573) related to berseem clover + 75% basil. The results concluded that the highest forage quality was obtained from berseem clover + 50% and 100% basil at integrated N fertilizer treatment.