Field experiments were carried out at University of Agricultural Sciences, Dharwad during kharif season for two years to study the influence of herbicide on physiological and bio physical parameters in potato cv. Kufri jyothi. The experiment consisted of 13 treatments comprising five herbicides viz. alachlor (1.0 and 1.5 kg ai/ha ), fluchloralin ( 1.0 and 1.5 kg ai/ha ), pendimethalin ( 1.0 and 1.5 kg ai/ha ), metribuzin ( 0.75 and 1.0 kg ai/ha ) and diuron ( 1.0 and 1.5 kg ai/ha ) compared with farmers practice , weed free check and unweeded control . The mean of  two years data indicated that the influence of herbicides on physiological and bio physical parameters of potato was similar. All the herbicides substancially increased LAI, LAD, total chlorophyll content photosynthetic rate and starch content. Pre emergence application of metribuzin @  0.75 kg ai/ha recorded higher LAI (2.82) LAD( 78.6 days ) , chlorophyll content (1.1385 mg/g fresh wt.), photosynthetic rate (28.0 u mol/m2/s) and starch content (68.0 % ).The lower LAI,LAD chlorophyll content, photosynthetic rate and starch content ( 2.088, 70.6 days,  0.9165 mg/g fresh wt, 22.7µmol/m2/s and 66.1%, respectively ) was recorded in unweeded control .