A field experiment was conducted at the Main Agricultural Research Station, University of Agricultural Sciences,Dharwad on medium black clay soil during two consecutive kharif seasons (2015 and 2016), to know the efficacy of fivepre-emergence (Alachlor 50 % EC @ 3.00 l a.i./ha, Pendimethalin 30 % EC @ 1.00 kg a.i./ha, Butachlor 50 % EC @ 1.00 kga.i./ha, Pendimethalin 38.7 CS @ 750 g a.i./ha and Oxyfluorfen 23.5 % EC @ 100 g a.i./ha) and four post-emergenceherbicides (Propaquizafop 10 % EC @ 100 g a.i./ha, Quizalofop ethyl 5 % EC @ 50 g a.i./ha, Fenoxaprop-p-ethyl 9.3 %EC @ 100 g a.i./ha and Imazethapyr 10 % SL @ 100 g a.i./ha) on control of weeds in groundnut and soybean. Higher weedcontrol efficiency of 96.22 to 97.93 and 97.10 to 98.40 per cent in respective groundnut and soybean crops was observedwith pre-emergence herbicides as compared to post-emergence herbicides (49.48 to 82.88 and 64.92 to 92.61, respectively).Among the pre-emergence herbicides in groundnut and soybean, Alachlor 50 % EC @ 3.00 l a.i./ha recorded higher weedcontrol efficiency (97.96 and 98.40 % in groundnut and soybean, respectively). Pre-emergence application of Butachlor 50% EC @ 1.00 kg a.i./ha in groundnut and Alachlor 50 % EC @ 3.00 l a.i./ha in soybean recorded lower weed index (5.46 and7.96, respectively). Post-emergence application of either Quizalofop-ethyl 5 % EC @ 50 g a.i./ha or Propaquizafop 10 %EC @ 100 g a.i./ha or Fenoxaprop-p-ethyl 9.3 EC % @ 100 g a.i./ha found more beneficial in controlling only annual grassyweeds with reduced weed number and weed biomass; increased weed control efficiency and decreased weed index. All theseherbicides did not show any phyto-toxicity symptoms on groundnut and soybean. Among the different pre and postemergenceherbicides, post-emergence application of Imazethapyr 10 % SL @ 100 g a.i./ha (a Imidazolinone group herbicide)was effective in controlling both annual grassy and annual broad leaf weeds either by partially killing them or by snubbingthe growth and development which in turn resulted in lower weed biomass, higher weed control efficiency and higher weedindex with significant phyto-toxicity symptoms on groundnut and soybean leading to reduced crop yields. Significantlyhigher dry pod yield and kernel yield of groundnut; and seed yield of soybean were noticed with weed free control treatment(4091, 3118 kg/ha and 2842 kg/ha, respectively) as compared to weedy check (3245, 2381 and 2172 kg/ha).