Penoxsulam was found effective especially against Echinochloa species and Cyperus difformis as compared to butachlor and pretilachlor and it recorded lower weed dry matter. Highest grain yield was obtained with penoxsulam at 22.5 and 25 g/ha at 3 DAT during 2005 and 2006, respectively. Penoxsulam at 22.5 and 20.0 g/ha was found better against weeds than butachlor and pretilachlor. Weedy plot recorded 41.0 and 34.3% lower grain yield as compared to the treatment having highest grain yield during both the years. Based on two-season studies, it can be concluded that penoxsulam at 20-25 g/ha applied as pre-emergence (3 DAT) as well as early post-emergence (10 DAT) effectively controlled weeds in transplanted rice and it had no phytotoxicity effect on rice crop upto 25 g/ha dose.