Population improvement of babycorn was practiced on varietal hybrid population of Suwan 3 and Babycorn Composite # 1 DMR, using one cycle of full sib selection. Varietal hybrid population (SW3 x B-C1) was selected and mated to form 176 full sib families, (SW3 x B-C1)-FS, which were grown for progeny test. The population had on the average 2.2 ears per plant and the yield of young ears with husk was 605 kg/rai while the yield of acceptable dehusked ears was 72 hg/rai. Based on the progeny test data of prolificacy and ear quality FS families were selected for 12.5 and 25.0 percent and assigned into 6 groups according to different FS. Each group was recombined to form the 6 populations and tested again and other 6 varieties to evaluate for progress from selection. It was found that the improved populations gave the same unhusked ears and marketable ear yields as the check entries. The overall average unhusked ear and marketable ear yields of the improved populations were 1394 and 253 kg/rai, respectively. The yields of each improved population were not different from the check entries and fell between the yeilds of Suwan 3 and Babycorn Composite # 1 DMR. The yield of young ears with husk and of the improved population was about 60% higher than that of Suwan 3 but about 26% lower than Babycorn Composite # 1 DMR. Moreover it yielded 66% more marketable young ears than Suwan 3 but 29 % lower than Babycorn Composite # 1 DMR.