The experiment was conducted to evaluate the effects of three sizes of sets viz., small (2.25g), medium (5.5g) and large (9.00g), and five growth regulators, namely IAA (200 ppm), GA3(100 ppm), NAA (200 ppm), CCC (500 ppm) and a control on the growth and yield of onion cv. Taherpuri. Large bulb produced the highest bulb yield (12.86t/ha) by increasing plant height, number of leaves per plant, bulb diameter and mean bulb weight. Smaller bulb produced higher proportion of single bulbs (62.53%) than larger ones. The growth regulators significantly increased the bulb yield compared with control treatment. Application of IAA at 200 ppm gave the best results on all the parameters except plant height. The highest bulb yield was recorded as 12.57t/ha from the plants sprayed with IAA at 200 ppm. The interaction effect of bulb size and growth regulators was not significant. The combined treatment of large bulb x IAA gave rise to the highest bulb yield (14.23t/ha). The highest gross income (TK. 3,13,060/ha) and net return (TK. 1,67,445/ha) were obtained from the treatment combination of large bulb x IAA and large bulb x NAA. But the highest benefit cost ratio (2.52) was found in the treatment combination of small bulb x NAA. The effects of growth regulators were found in order of IAA>GA3>NAA>CCC.