Poznan is a city in west-central Poland with over 500,000 inhabitants. Located by the Warta River, it is one of the oldest cities and the fourth largest industrial centers in Poland. The aim of this study was to determine the distribution of mercury in surface and ground waters in Poznań. Total mercury concentrations have been determined in surface waters (ponds, lakes, streams and rivers) and ground water collected in 2003 and 2004. Mercury was determined using the cold vapor atomic fluorescence spectrometry method (CV-AFS). The results of the study have shown that mercury distribution in the samples of surface and ground water collected from various sites in Poznań are relatively uniform. Total mercury concentration was 20 ± 8 ng/L (range 8 – 40) in the surface water and 1.3 ± 0.7 ng/L (range 0.8 – 4.1) in ground water.