Comparative efficacy of penoxsulam against weed control in transplanted rice was studied at Agricultural Research Station, Ummedganj, Kota (Rajasthan). The experiment was laid out in randomized block design with 7 treatments and 4 replications. Results revealed that the major weed flora associated with the transplanted rice were grasses likeEchinochloa colonum and Echinochloa crusgalli; sedges like Cyperus rotundus, Cyperus difformis and Cyperus iria; and broad-leaved weeds like  Eclipta alba and Ammenia baccifera. Penoxsulam at 0.0250 kg/ha applied at 0-5 days after transplanting was most effective to check all types of weed growth. This treatment also gave the maximum grain yield and straw yield,  resulting in the lowest weed index, dry weight of weeds, weed persistence index and highest herbicidal efficiency index