Samples collected from 15 broiler farms(47 flocks, 920 1-day-old chicks) during March to December, 2006, To survey serum antibody titers of NDV, IBDV and MG/MS, the antibodies of ND viruses were detected by HI test and ELISA, against antibodies of IBD viruses and MG/MS by ELISA. The antibody titers of NDV showed 6.4, HI and 6,968, ELISA, respectively. The rate to below protective antibody levels(${ge}5$, HI and ${ge}1,000$, ELISA) were 8%, HI, 5%, ELISA, specially, Baeksemi were 22%, HI, 14%, ELISA. The rate of positive by ELISA showed 99%(914/920). The ELISA titer of IBDV showed mean titer 3,890. The rate of positive were 93% (857/920), specially, Baeksemi were 84%. The ELISA titers of MG/MS showed mean titer 5,666. The rate of positive were 78% (715/920) and 100%, Abor-Acre, 97%, Baeksemi, respectively. The antibodies not detected from 18%, ELISA titers was varied from 500 to 20,000. At antimicrobial susceptibility of E coli, Staphylococcus spp and Salmonella spp isolated from 1-day-old chicks, E coli were susceptible to AmC, AM, NOR, SXT, ENR, CIP, Staphylococcus spp were susceptible to AmC, SXT, AM, ENR and Salmonella spp were susceptible to AM, AmC, SXT and P.