A simple high-performance thin layer chromatographic (HPTLC) method has been developed for the determination of atrazine and simazine herbicides in drinking and surface waters. The method involves solid-phase extraction on C 1 8 Bakerbond cartridges followed by development of the concentrated extracts on HPTLC silica plates with a nitromethane-tetrachloromethane (1:1, v/v) mobile phase and quantitation by UV scanning densitometry. Using the proposed mobile phase composition, pronounced background suppression on the chromatograms of the real water samples was accomplished. The detection limits of the method were 30 and 60 ng/l for atrazine and simazine, respectively, at the 80-400 ng/l fortification level in the surface waters. The method was successfully applied to the analyses of tap and surface waters with overall recoveries between 58 and 93% and a relative standard deviation below 12%. The results show, that the HPTLC method is sufficiently selective and sensitive to be employed in screening of contaminated waters containing the triazines below the maximum residues limits of the European Community.