The performance of four legume species used as green manure for the production of biomass and its interference in the community of weeds, had been analyzed. The experiment was conducted in the city of Tangará da Serra (MT), from October 2010 to January 2011. The experimental design was a randomized block design with five replications. The treatments consisted on the following green manures: Crotalaria juncea L., Crotalaria spectabilis Roth, Mucuna aterrimum Piper & Tracy and Canavalia ensiformis (L.) DC. M. aterrimum showed higher production of green matter (40.63 t ha-1), while C. juncea was distinguished by a dry matter production (10.49 t ha-1). The weeds had lower dry matter accumulation under the green manure M. aterrimum (0.73 t ha-1).