Abstract. Since trace organic compounds such as pharmaceuticals in surface water have been a relevant threat to drinking water supplies, in this study removal of pharmaceuticals and transformation of pharmaceuticals into metabolites were investigated in the main source of micropollutants such as WWTPs and engineered constructed wetlands. Pharmaceuticals were effectively removed by different WWTP processes and wetlands. Pharmaceutical metabolites with relatively low log D value were resulted in the low removal efficiencies compared to parent compounds with relatively high log D value, indicating the stability of metabolites. And the constructed wetlands fed with wastewater effluent were encouraged to prevent direct release of micropollutants into surface waters. Among various pharmaceuticals, different transformation pattern of ibuprofen was observed with significant formation of 1-hydroxy-ibuprofen during biological treatment in WWTP, indicating preferential biotransformation of ibuprofen. Lastly, transformation of pharmaceuticals depending on their structural position was investigated in terms of electron density, and, the electron rich C₁ = C₂ bond of carbamazepine was revealed as an initial transformation position.