Uptake and elimination of 3,4-dichloroaniline by rainbow trout (Oncorhynchus mykiss) and golden ide (Leuciscus idus melanotus) were investigated in tap water and in water of the river Rhine. For describing the uptake of 3,4-dichloroaniline we used a first order one-compartment model whereas for elimination a first order two-compartment model was fitted to the data. Bioconcentration factors showed little differences, and ranged from 20 to 31. Elimination was slower in golden ide than in rainbow trout. We found no differences in the elimination of 3,4-dichloroaniline in tap or river water. So our results indicate that elimination is not influenced by the different water types.