A field experiment was conducted during Rabi seasons of 2008 and 2009 at Crop Research Center of GBPUA&T, Pantnagar (Uttarakhand) to study the effect of fenoxaprop-p-ethyl 9 EC for grassy weed management in onion and its residual effect on succeeding maize crop. All treatments reduced the density of major weed species of onion and dry weight of weeds. Yield attributes and bulb yield were increased significantly over unweeded check. Application of fenoxaprop-p-ethyl 78.75 g/ha was the best tretment and subsequently recorded maximum bulb yield of onion as compared to other doses of fenoxaprop-p-ethyl (56.25, 67.50 g/ha) and quizalofop-p-ethyl 37.5 g/ha. This herbicide did not show any phytotoxic effect on onion crop. Similarly, post-harvest study on succeeding crop of maize indicated the absence of no residual phytotoxic effect of fenoxaprop-p-ethyl tested in onion.