Abstract: An experiment to determine the effect of nitrogen alone and in combination with phosphorus on the growth and yield of Brassica Juncea L.Cv. The N - P levels (kg ha–1) 0-0, 50-0. 100-0, 50-50, 100-50 and 150-50 were applied. The results revealed that plant height at maturity, number of branches, number of pods per plant, number of seed per pod and 1000 seed weight were affected significantly by N and N-P levels. Application of N-P at 100-50 kg ha–1 gave the highest seed yield. It was also noted that application of nitrogen over 100 kg ha–1 did not produce higher seed yield then 100-50 kg ha–1 N-P application.