A field experiment was conducted during rainy (kharif) seasons of 2005 and 2006 at Jabalpur to assess the efficacy of penoxsulam as pre-emergence (5 days after transplanting–DAT) and early post-emergence (10 DAT) in transplanted rice (Oryza sativa L.). The major weeds were Echinochloa colona, Cyperus spp., Ammania baccifera, Lindernia crustacea, Eriocaulon spp., Caesulia axillaris, Alternanthera sessilis and Commelina spp. Infestation of weeds reduced grain yield of rice by 25.9%. Penoxsulam 22.5 g/ha applied at 10 days after transplanting was found most effective in controlling weeds and maximizing rice grain yield (6287 kg/ha). Early post-emergence application (10 DAT) of penoxsulam was better than its pre-emergence application (5 DAT) in increasing grain yield. Grain yield of rice was significantly and negatively correlated (r = -0.82) with weed dry matter.