An experiment was conducted at the Horticulture Farm of the Bangladesh Agricultural University, Mymensingh during the period from July 2003 to January 2004. The objectives of the study was to examine the influence of set sizes including whole and cut pieces in order to develop a low—cost technology for onion production. The results of the experiment revealed that bulb yield increased with the increase .in bulb size with proportionate increase in the production cost. Cut bulbs treated with ash had no effect on yield of onion bulbs. The yield of plants raised from whole bulbs was higher than that raised from cut bulbs irrespective of size. Small whole bulbs were more profitable for commercial onion production followed by very small whole bulb and cut pieces from large bulbs.