Field experiments conducted during summer seasons for four years (2002, 2003, 2004 and 2005) and during kharif seasons for three years (2002, 2003 and 2005) showed that unchecked weeds caused a reduction of 41.2 and 41.6% in blackgram yield during the two respective seasons. In summer season, pendimethalin 0.75 kg/ha, pendimethalin 0.45 kg/ha+hand weeding (HW) 25 days after sowing (DAS), fluchloralin 0.675 kg/ha, two HW 25 & 40 DAS and weedy check recorded weed dry matter of 4.87, 3.45, 5.87, 3.40 and 23.6 q/ha and grain yield of 11.47, 11.75, 10.72, 11.95 and 7.02 q/ha with net returns of Rs. 10033, 10035, 9401, 9330 and 4828/ha, respectively. In kharif season, the respective treatments had weed dry matter of 4.16, 4.26, 4.93, 2.90 and 20.9 q/ha and grain yield of 10.43, 10.76, 10.60, 11.76 and 6.86 q/ha with net returns of Rs. 8577, 8649, 9233, 9064 and 4604/ha.