Fish caught in waters polluted with paper mill effluents have been analysed by a gas chromatographic headspace technique in order to identify the organic compounds causing the strong off-flavour present in the fish. Both chemical and sensory analyses were done and the results compared. The concentrations of off-flavour volatiles present in the different fish samples showed good correlations with the degree of off-taste found by sensory analyses. Typical organic compounds from paper mill effluents such as terpenes and their derivatives caused strong off-flavour, whilst low concentrations of haloforms and other halogen-containing compounds were found.