1. Seven chlorinated anilines and one chlorinated benzene were tested for their ability to bioconcentrate in guppies (Poecilia reticulata) under different experimental conditions. 2. Interactions between compounds in a mixture influence the bioconcentration of some chlorinated anilines. These interactions result in either an increase or a decrease of bioconcentration, depending on the compound studied. 3. Exposure concentration can have an effect on the extent of bioconcentration of some chlorinated anilines.