A field experiment was conducted at Mahatma Phule Krishi Vidyapeeth, Rahuri, Maharashtra, India  for two consecutive Rabi seasons 2011 and 2012 to find out most suitable and efficient combination of different pre-plant and post-emergence herbicides to control weeds in onion seed production crop. Experiment was conducted in randomized block design with 9 treatments and three replications consisting of pre-plant application of pendimethalin, post-emergence application of oxyfluorfen and quizalofop-ethyl and their different combinations. The pre-plant application of pendimethalin 0.750 kg/ha followed by post-emergence application of oxyfluorfen 0.250 kg/ha mixed with quizalofop-ethyl 0.050 kg/ha resulted in effective control of various broad-leaf and grassy-weeds and recorded lower weed density, weed biomass, weed index and higher weed control efficiency. This treatment also produced higher number of umbels per plant, plant dry matter, number of seeds per umbel, seed weight per umbel, 1000 seed weight and longer flowering stalk, and diameter of umbel. It also produced higher seed yield (439.30 kg/ha), gross return (` 329,475/ha), net return (` 192,450/ha) and B:C ratio (2.40) over all the other chemical weed control treatments.