A liquid/liquid extraction method coupled with a GC/MS analysis was optimized to quantify 27 polycyclic aromatic compounds in groundwater from contaminated sites. The aim was to optimize an analytical method to determine Polycyclic Aromatic Hydrocarbons (PAH) and Oxygenated Polycyclic Aromatic Compounds (O-PACs) in water and for apply the method to ground water samples collected from contaminated sites. The analysis takes place in one run, including dissolved as well as colloid and particle-associated compounds. Artificially contaminated waters were prepared with two concentration ranges from 0.01 to 1 mu g L-1 and 0.5 to 50 mu g L-1. This method proceeds with two main steps. The first step is a liquid/liquid extraction with dichloromethane followed by a concentration procedure. The second step is the injection for separation and quantification in a gas chromatograph coupled with a mass spectrometer. The novelty of this work concerns the control of each step by the introduction of deuterated standards in order in order to estimate the recoveries during the extraction, concentration and injection in the process as well as the possibility of quantifying PAC total concentrations in water. This method leads to very good quantification limits ranging from 1 to 60 ng L-1 for PAHs and from 10 to 1,200 ng L-1 for O-PACs, respectively. High sensitivity has been achieved with some of the PAHs with a good R (2) factor higher than 0.994 in the concentration range 0.01 to 1 mu L-1.