A field experiment was conducted during Kharif season of 2009 and 2010 to study t-he effect of pre- and post-emergence herbicides on weeds, growth, symbiotic traits and grain yield of greengram. Postemergence application of imazethapyr at 75 g/ha 17 days after sowing was found to be effective for controlling sedges, grassy and broad-leaf weeds as well as in improving grain yield of greengram and net returns whereas imazethapyr at lower doses (25 and 40 g/ha), did not control weeds effectively. Weed free and two hand weeding treatments gave higher grain yield than the other treatments during both the year. Imazethapyr at 25, 40 and 75 g/ha and pendimethalin at 0.75 and 1 kg/ha had negative effect on different symbiotic parameters such as nodule number, dry weight and leghaemoglobin content as compared to two hand weeding.