The short term (24-hr) and long term (21 days) effects of copper, cadmium, fenbendazole and sulfathiazole on the survival of the Korean fairy shrimp Branchinella kugenumaensis were evaluated. The 24-hr median lethal concentrations (LC50) of copper, cadmium, fenbendazole, and sulfathiazole were 39, 512, 182, and 31,818 μg/L, respectively. The toxicity of copper is highest among 4 chemicals used in this study, while sulfathazole the lowest. After the long term (21 days) exposure experiment, the LC50 copper, cadmium, fenbendazole, and sulfathiazole were 1.12, 2.1, 0.1, 6.6 μg/L, respectively. The long term effects of antibiotics were highly enhanced while the short-term effects were not strong. The sensitivities of B. kugenumaensis to copper and cadmium were higher than or comparable to those of other freshwater branchiopods (Streptocephalus spp., Thamnocephalus sp.), and far higher than the marine species (Artemia sp.). There were significant effects on the survival of B. kugenumaensis after long term exposure to relatively lower concentrations of copper, cadmium, fenbendazole and sulfathiazole. Therefore, B. kugenumaensis seems quite a good candidate species for the ecotoxicological assessments of freshwater environments.