Bioaerosols generated from wastewater treatment plants may create health risks for plant workers and nearby residents. To determine the levels of culturable airborne bacteria and fungi in bioaerosols, samples were seasonally collected above and near the aeration tanks of one feces-urine and three sewage treatment plants in Ulsan, Korea with an impaction-type sampler. In the feces-urine treatment plant, concentrations of heterotrophic bacteria were between $1.3({pm}0.2){ imes}10^3$ and $2.6({pm}1.2){ imes}10^4$ MPN/$m^3$ above the aeration tank and between $1.7({pm}1.0){ imes}10^2$ and $7.2({pm}2.2){ imes}10^3$ MPN/$m^3$ near the aeration tank. Coliform bacteria were detected both above and near the aeration tank. In cases of sewage treatment plant, the numbers of heterotrophic bacteria ranged from $1.9({pm}1.2){ imes}10^1$ to $1.8({pm}1.2){ imes}10^4$ MPN/$m^3$ above the aeration tank and from $5.0({pm}2.8){ imes}10^0$ to $6.6({pm}2.0){ imes}10^3$ MPN/$m^3$ near the aeration tank. At reference sites, the concentrations of heterotrophs in ambient air were measured between $7.0{ imes}10^0$ and $2.7{ imes}10^1$ MPN/$m^3$. When we isolated and tentatively identified heterotrophic bacteria, Pseudomonas luteola was the most dominant species in bioaerosols from wastewater treatment plants, whereas the most abundant one in reference samples was Micrococcus sp. When we measured fungal concentrations in bioaerosols, they were rather similar regardless of sampling locations and seasons, and such genera as Cladosporium, Alternaria, and Penicillium were commonly identified.