A field experiment was conducted at Norman E. Borlaug, Crop Research Center GBPUA&T, Pantnagar to evaluate the efficacy of quizalofop-ethyl market sample (MS) and sponsor sample (SS) in managing grassy weed flora in groundnut. Result revealed that that application of quizalofop-ethyl 5% EC (SS) at 50 g/ha resulted in significantly higher kernel yield (0.98 t/ha) which was at par with its market sample applied at the same dose. Density and dry matter accumulation of weeds was also minimum by the application of these herbicides. However the highest kernel yield was obtained under the weed free situation. Lower weed density, weed dry weight, weed persistence index and weed index in the plots where quizalofop-ethyl (SS) at 50 g/ha was applied. Higher weed control efficiency and herbicidal efficiency index, economic return were recorded under quizalofop-ethyl 5% EC (SS) at 50 g/ha as compared to standard check imazethapyr 150 g/ha. Thus, the post-emergence application of quizalofop-ethyl 5% EC (SS) at 50g/ha seemed to be more beneficial with high productivity and economic return owing to effective weed control.