Field experiments were conducted during winter seasons of 2008-09 and 2009-10 at Eastern Block Farm, Tamil Nadu Agricultural University, Coimbatore to study the efficiency of new formulation of pre-emergence herbicide pendimethalin 38.7% on growth and development of cotton with better weed management in a cost effective manner, under irrigated condition. Pendimethalin 38.7% was tried in four different doses, viz. 1.5, 2.0, 2.5 and 4.0 kg/ha and it was compared with pendimethalin 30% 1.0 kg/ha, early post-emergence herbicide trifloxysulfuron, power weeders and hand weeding. The pre-emergence application of pendimethalin (38.7%) at 2.0 kg/ha at 3 days after seeding (DAS) followed by hand weeding and earthing at 45 DAS did not show any phytotoxic effect on cotton and recorded lower weed density and biomass with increased the seed cotton yield by about 41.5% over unweeded control and higher net returns.