An experiment was conducted during Kharif season of 2009 at BHU, Varanasi to evaluate the bio-efficacy of imazethapyr 10% SL + surfactant against important weeds of groundnut. Application of imazethapyr  200 g/ha + surfactant being at par with its lower rates of 100 and 125 g/ha, reduced the density of dominant weeds. Pre-emergence application of oxyfluorfen 250 g/ha effectively controlled the Dactyloctenium aegyptium and Trianthema portulacastrum whereas, it was least effective against Echinochloa colona and Cyperus rotundus. Imazethapyr  200 g/ha + surfactant recorded significantly the highest seed and haulm yield and weed control efficiency over imazethapyr 100 g/ha + surfactant (market sample), imazethapyr 75 g/ha + surfactant and oxyfluorfen 250 g/ha. There was no-phytotoxicity symptoms on crop even at higher rate (200 g/ha) of the herbicide.