Phenols in waters and soil leachates were selectively determined down to sub-ng ml^–1 levels by a continuous-flow spectrophotometric method. The analytes were preconcentrated and separated from the sample matrix by on-line absorption onto a commercially available absorbent column (Amberlite XAD-4) at pH 2.0 in a flow system. Aromatic amines potentially interfering with detection were not retained and thus posed no problem. Retained analytes were eluted by continuously pumping an aqueous stream at pH 13.0, the eluent being directly introduced into the determination flow system (4-aminoantipyrine method). The reaction product was subsequently extracted into the organic phase (chloroform) for detection after continuous liquid–liquid extraction, which made the over-all assay very sensitive. The calibration graph was linear over the range 0.5–60 ng ml^–1 and the detection limit was 0.2 ng ml^–1. A throughput of 8 samples h^–1 was achieved for a preconcentration time of 5 min.