A field experiment was carried out to study the effect of pendimethalin, imazethapyr and paraquat on plant growth and seed yield of pigeonpea. It was found that  maximum increase in seed yield and B:C were obtained with pendimethalin as pre-emergence (PE) 1.0 kg/ha followed by (fb) paraquat 0.40 kg/ha at 8 weeks after sowing (WAS). The next best treatments were pendimethalin as PE 1.0 kg/ha fb paraquat 0.40 kg/ha 6 WAS, imazethapyr 0.075 kg at 20 days after sowing (DAS) fb paraquat 0.40 kg at 6 WAS and imazethapyr 0.075 kg at 20 DAS fb paraquat 0.40 kg at 8 WAS. Similar trend accrued with the economic returns, but B:C  was highest in  pendimethalin as pre-emergence 1.0 kg/ha fb paraquat 0.40 kg/ha at 8 WAS (2.50) followed by imazethapyr 0.075 kg/ha fb paraquat at 6 WAS (2.25) and 8 WAS (2.25) and pendimehalin as PE 1.0 kg/ha fb paraquat 6 WAS (2.20).