Trinitrotoluene (TNT) has been extensively used as an explosive. A water system in Sweden was investigated due to heavy TNT contamination. Sediment and water samples were taken along a creek all the way to a downstream pond. Screening for TNT and degradation products such as 2-amino,4,6-DNT and 4-amino,2,6-DNT, was performed using GC-ECD analysis. TNT concentrations varied between 0.05 g/kg up to ca 230 g/kg (dry weight) in creek sediment, whereas the pond sediment contained 6-10 g/kg TNT. This indicated a considerable precipitation of TNT in the creek and close to the inflow of the pond. The pond water contained 3 mg/L of TNT. Toxicological analyses revealed clear responses in all toxicological models used. Cell cultures were affected at a 50 % addition of extract at all sediment sampling points. Water fleas showed acute effects at a 6 % addition of water extract (approx. 10 mg/L). Increased mortality in salmon alevins already occurred at 5 times dilution (0.4 mg TNT/L) of pond water. A dose-dependent uptake in the interval 0.016-2 mg TNT/L and a time-dependent uptake at 0.08 mg TNT/L and its metabolites were documented. However, the disturbed physiological condition and delayed development in alevins were not objects of study and could not be excluded even at 125 times diluted pond water (0.016 mg TNT/L).