The occurrence and fate of trace - level contamination of pharmaceuticals in the aquatic environment has been recognized as one of the emerging issues in environmental chemistry. The effluents of wastewater treatment plants, usually directly emitted to the environment, often contain the anti-inflammatory drug diclofenac. Diclofenac was chosen because it is of high consumption; by background literature indicate toxic effects on biota and the lack of profile in sewage removal provided by the city. For this purpose, a survey on the presence of diclofenac in urban wastewater of Rio de Janeiro was carried out. It were evaluated diclofenac concentration in the affluent and effluent from wastewater treatment plant (WWTP) Penha and Ilha do Governador, Rio de Janeiro, Brazil. Samples were collected along the line of treatment of each WWTP, and for clean up the samples were solid phase extraction (SPE), analysed by high performance liquid chromatography (HPLC), assisted by diode array detector (DAD) techniques. The removal efficiency of pharmaceuticals in the wastewater treatment plants was roughly evaluated. Diclofenac was detected in all samples analysed wastewater (treated and raw), which confirms the low removal efficiency of conventional treatment systems, aerobes and anaerobes.