A field experiment was conducted during kharif season of 2013 in Medicinal Plant Research and Development Centre (MRDC), G.B. Pant University of Agriculture and Technology, Pantnagar to evaluate weed dynamics, herbage and oil yield of sweet basil (Ocimum basilicum) under various weed management practices. The experiment was laid out in a randomized complete block

design with three replications to evaluate ten treatments viz. weedy check, weed free, manual weeding at 30 Days After Transplanting ( DAT), manual weeding at 30 and 60 DAT, straw mulch (5 cm), straw mulch (8 cm), polythene mulch (100 gauge), polythene mulch (160 gauge), pre emergence application of pendimethalin @ 0.5 kg ha-1 and pendimethalin @1.0 kg ha-1. The major weed species in the experimental plot were Echinochloa colona, Echinochloa crusgalli, Dactyloctenium agyptium, Eleusine indica, Caesulia axillaris, Celosia argentea and Cyperus rotundus, Echinochloa spp and Cyperus spp constituting of 42.8 and 49.4 per cent respectively, of the total weed population in weedy check plot at 100 DAT. Maximum weed population and dry matter was recorded under weedy check followed by pendimethalin @ 0.5 kg ha-1 and pendimethalin @1.0 kg ha-1. Among all the treatments, weed free treatment followed by polythene mulch 160 gauge thickness was the most effective in minimizing weed population and dry matter. Weed free treatment recorded the highest fresh herbage and oil yield (5316 kg ha-1 and 22.41 kg ha-1, respectively) followed by polythene mulch with 160 gauge thickness (5220 kg ha-1 and 22.10 kg ha- 1, respectively) and the lowest with weedy check (2974 kg ha-1and 11.29 kg ha-1,  respectively). The highest benefit cost ratio was recorded with non chemical method of 160 gauge thickness of polythene mulch and it can be used as an alternative weed management practice, particularly, when labour is limiting factor in cultivation.