Phthalates are a group of chemical compounds with increasing interest from the analytical point of view. The risks for human health associated with some of these compounds have unleashed the necessity to develop analytical methods with great sensitivity that allow us to detect their presence at trace levels in order to assure protection for the population. A simple and rapid method for determining a group of phthalate esters in aqueous samples was developed. The method was based on high-performance liquid chromatography-(electrospray)-mass spectrometry (HPLC-ES-MS), working in positive ionisation (PI) mode. A gradient elution was performed with acetonitrile-ultrapure water starting from 5 to 75% acetonitrile in 5 min followed by isocratic elution during 5 min. Standard calibration curves were linear for all the analytes over the concentration range 10-500 ng mL(-1). The LOD values found for DMP, DEP, BBP and DBP were 0.8, 3.4, 0.6 and 1.2 ng mL(-1) respectively. The relative standard deviation ranged from 0.8 to 1.7%, which indicated good method precision. The proposed analytical method has been applied to the analysis of commercial physiological saline solutions in order to check the presence of phthalates and to determine their concentration.