In the recent years of labour and water scarcity, most of the rice cultivating areas all over the world are in a desperate need to save the resources and to find suitable alternatives so as to budge from transplanted rice cultivation. Direct seeded rice (DSR) cultivation is one of the best alternative. The vast spectrum of weeds present in this DSR ecology causes a voluminous decrease in the crop yield. In order to curtail the weeds, chemical management using broad spectrum herbicides which can control all classes of weeds is the efficient and economic way. On using broad-spectrum herbicide it may cause crop injury. In this regard TNAU has developed a novel herbicide (Imazethapyr) tolerant rice mutant (HTM Robin) through EMS mutagenesis of Nagina 22 cultivar. Robin mutant was tested across the location against the herbicide Imazethapyr and found to be tolerant and was registered at NBPGR, New Delhi. In this study the efficacy of this herbicide tolerant mutant was tested under chemical weed management. The genotypes CO51, HTM, Nagina 22 were raised in the weed free and control plots. Certain traits such a total number of tillers, number of productive tillers, grain yield/plant, straw yield/plant, number of filled grains/panicle, plant height, panicle length, 1000 grain weight, spikelet fertility were observed in the weed free and the control plots. Significant difference was observed for certain traits between the weed free and control plots. There was a vast reduction in the dry weight of the weeds in the herbicide sprayed plot when compared to the control plot. The weed control efficiency of the herbicide was found to range (Imazethapyr) from 74-92%.