The performance of biological treatment processes for saline wastewater is usually low due to adverse effects of salt on microbial flora. High salt concentrations in wastewater cause plasmolysis and loss of cell activity, thereby resulting in low (COD) removal efficiencies, In order to quantify the adverse effects of salt on biological treatment of saline wastewater a synthetic wastewater composed of dilute molasses, urea, KH2PO4, and various concentrations of salt (1-5% NaCl) was treated under aerobic conditions in a biological reactor by fedbatch operation. Zooglea ramigera was used as the dominant culture throughout the studies. Variations in the COD removal rate and the efficiency with salt concentration were determined. A rate expression indicating the inhibition effects of salt was proposed. Kinetic constants were determined by using experimental data.