An experiment was conducted to assess the efficacy of different weed management practices in rice grown under the System of Rice Intensification (SRI) in comparison with the conventional system. The study was carried out during 2007 and 2008 in the lateritic sandy clay loam soils at Pattambi, Kerala. Density and dry weight of weeds were higher in SRI especially when weed control was done through repeated cono weeding, while they were lower in the conventional system. Conventional system with cono weeding at 10 DAT followed by hand weeding at 30 DAT, and post-emergence herbicides alone reduced the weed dry weight significantly. Net returns and B:C ratio were also the highest in the conventional system with post-emergence application of cyhalofop-butyl  0.1 kg/ha followed by metsulfuron-methyl  + chlorimuron-ethyl. In SRI, the weed density and dry weight were the lowest with pre-emergence herbicide followed by hand weeding at 30 DAT, and cono weeding at 10 DAT followed by post-emergence herbicides. However, weed control with post-emergence application of cyhalofop-butyl, followed by metsulfuron-methyl + chlorimuron-ethyl gave higher B:C ratio in both systems.