Diaion HP-20 was used for on-line separation/preconcentration and determination of lead by flow injection flame atomic absorption spectrometry. Lead is preconcentrated at pH 9 as its 1-nitroso-2-naphthol (NN) complex onto mini column. The elution step is performed with a stream of 1 M HNO3 at 3.0 ml/min and lead displaced is introduced directly into the nebuliser of flame atomic absorption spectro-meter. The proposed method was successfully applied to the determination of lead in a stream sediment reference material (23.9 +/- 0.12 mug/g certified value: 23.0 mug/g) and natural water samples. The detection limit (3sigma) was 2.0 mug/l for preconcentration at 3.0 ml/min. The recoveries of spike additions to drinking water sample were greater than 95%.