Macrophomina phaseolina (Tassi) Goid. is a common pathogen causing stem blight of cowpea in Rajasthan. The role of antagonists in curtailing the growth of M.phaseolina in mung has been established (Kehri and Chandra, 1991). In the present paper, the efficacy of Trichoderma viride Pers. ex Fr. in controlling the stem blight of cowpea is reported.