Selection indices were constructed using seven traits in a set of 32 forage oat (Avena sativa L.) genotypes using Smith index. The experiment was conducted with three replications at Instructional Dairy Farm, G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand. The efficiency of different indices was assessed in terms of expected genetic advance and relative efficiency of selection over grain yield per se. Efficiency of indices over direct selection for relative selection efficiency ranged from 16.92 to 514.28 percent. Selection on the basis of number of spikelets per panicle gave 43.16% higher efficiency for grain yield improvement. This trait was found important for all the indices that also had high heritability, high GCV and direct effect on grain yield per plant. Selection indices comprising of growth rate, number of spikelets per panicle and grain yield were most efficient indices for grain yield improvement with relative efficiency of selection as 374.53 percent and genetic advance of 24.12.