A Field experiment was conducted at Agricultural Research Station, Bhavanisagar of Tamil Nadu Agricultural University during Rabi 2013-14 to study the bio-efficacy evaluation of flumioxazine for weed control in soybean. Higher weed control efficiency was obtained with pre-emergence application of flumioxazine at 250 g/ha followed by its lower dose of 150 g/ha. Among the treatments, pre-emergence application of flumioxazine at 112.5 g/ha recorded increased yield and economic returns in soybean. Hence, the pre-emergence application of flumioxazine at 112.5 g/ha was found to reduce the weed density below the economic threshold level and increased the yield and net return in soybean without any phytotoxic effect on the crop and residual effect on the succeeding crop.