A field experiment was conducted during summer season at University of Agricultural Sciences, Dharwad to study the influence of herbicides on physiological and biochemical  traits in radish.  All the herbicides the significantly increased the  LAI and LAD, total chlorophyll content, photosynthetic rate and nitrate reductase activity compared to unweeded control. Among the herbicides butachlor @ 1.5 kg ai ha-1 recorded highest weed control efficiency (67.1%)and more chlorophyll content(1.045 mg g-1 fr wt.) photosynthetic rate (25.6 m co2 m-2 s-1), nitrate reductase activity (171.2 u moles of NO2 formed/ g fr. wt.)  and root yield.(607.6 q ha-1). While, unweeded control recorded lowest chlorophyll content (0.741 mg g-1 fr wt.),  photosynthetic rate (13.5 m co2 m-2 s-1), nitrate reductase activity (76.4  u moles of NO2 formed/ g fr. wt.)   and root yield.(292.7 q ha-1)