The frequency of second chromosome bearing deleterious and sterile genes in natural population Drosophila melanogaster was estimated by using of cy/pm method. (1) The frequency of deleterious genes of Drosophila melanogaster was estimated to be 65.7 per cent from Ulsan population. The frequency in Ulsan is the highet among four (2) Allelism rates of lethal genes extracted from Anyang, Kimpo, Jeoju. and Ulsan population were calculated to be 1.45, 5.02, 10.2 and 9.3 per cent, respectively. (3) The frequency of sterile genes of Drosophila melanogaster was 4∼5 percent. (4) The frequency of phenotype sterile genes in household population was 3.11 per cent.