The present research was conducted to assess the treatment performance of two natural treatment systems constructed in Kayseri province of Turkey. Influent and effluent wastewater samples were subjected to biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), pH, electrical conductivity (EC), total kjeldahl nitrogen (TKN) and total phosphorus (TP) analyses. Effluent BOD5 concentrations varied between 40-110 mg/L, COD concentrations varied between 287-402 mg/L, pH values between 7.18-8.04, EC values between 1571-2870 mu/cm. The pH values of all samples met the discharge criteria specified in water pollution control regulations. COD and pH values exhibited an irregular trend with the months. Influent TSS values varied between 75-99 mg/L and effluent TSS values varied between 64-84 mg/L and effluent TSS concentrations were meeting the discharge criteria. Effluent COD concentrations of one of the systems were also meeting the discharge criteria. Effluent total phosphorus values were above the discharge limits. Considering the parameters not able to meet the discharge criteria, it was concluded that these systems should either be repaired or rehabilitated to eliminate the deficiencies experienced in practice.