A field experiment was conducted during kharif 2008 and 2009, to study the effect of different pre-and post-emergence applications of herbicide on weed infestation and grain yield of soybean [Glycine max (L.)Merr.]. Among the different herbicides, the highest seed yield was recorded with lone application of diclosulam 18 g/ha as pre-emergence supplemented with one hand weeding at 20 DAS and application of diclosulam 18 g/ha as pre-emergence followed by haloxyfop 100 g/ha as postemergence. However, these were significantly at par with weed-free treatment. The highest weed control efficiency and the lowest weed biomass were recorded in weed-free treatment followed by application of diclosulam 18 g/ha as pre-emergence with one hand weeding at 20 DAS. Application of diclosulam as pre-emergence also performed better over the standard check either applied pendimethalin as pre- or post-plant incorporation of fluchloralin before the sowing of the seed.