An investigation on the effect of green manuring in rice – wheat cropping system was undertaken at the experimental farm in Bidhan Chandra Krishi Viswavidyalaya, Kalyani, West Bengal, in consecutive three seasons during May 2001 to March 2002. Four green manure crops viz Sesbania rostrata, Sesbania aculeata, Vigna sisensis and Crotalaria juncea were grown during summer (Kharif) followed by rice (variety Annada) under direct seeded rainfed condition in Kharif and wheat (variety UP 262) in irrigated condition during dry season. Results revealed that green manuring and its residual effect increased all the growth attributes like plant height at harvest, dry matter accumulation, leaf area index, crop growth rate, yield components like number of panicles m^-2, number of filled grains panicle^-1, grain and straw yield of rice and succeeding wheat compared with control. However, both the Sesbania sp. was found the best among the different green-manuring crops. The highest rice grain yield (3 t ha-1) and wheat grain yield (3.4 t ha^-1) were obtained when grown in sequence with Sesbania rostrata.