This paper presents the results of a survey of the wastewater effluent and surface waters of the lower river Tyne, UK. Samples were analysed by reversed-phase high-performance liquid chromatography-electrospray tandem mass spectrometry following solid phase extraction, for the presence of 13 pharmaceuticals selected from the priority lists of the UK Environment Agency and the Oslo and Paris Commission (OSPAR). The pharmaceutical compounds measured were acetyl-sulfamethoxazole, clofibric acid, clotrimazole, dextropropoxyphene, diclofenac, erythromycin, ibuprofen, mefenamic acid, paracetamol, propranolol, sulfamethoxazole, tamoxifen and trimethoprim. Of the wastewater treatment works (WTW) samples (n=9) analysed, all compounds except sulfamethoxazole and acetyl-sulfamethoxazole were detected at concentrations ranging from 11 to 69,570 ng l(-1) (in raw effluent). In the surface water samples (n=18), clotrimazole, dextropropoxyphene, erythromycin, ibuprofen, propranolol, tamoxifen and trimethoprim were detected at concentrations ranging from 4 to 2370 ng l(-1). Results of this study show that various pharmaceutical compounds are effectively reduced during their passage through a tertiary wastewater treatment works, whilst others are sufficiently persistent to occur in estuarine systems.