Ambersorb 563 adsorption resin was used for on-line separation/preconcentration and determination of copper by flow injection flame atomic absorption spectrometry. Copper was quantitatively recovered from the model solutions on mini column at the appropriate pH without adding chelating reagent. The elution step was performed with a stream of 0.25 mol L-1 HNO3 at 5.0 ml, min(-1), which introduced copper directly into the nebuliser of the flame atomic absorption spectrometer. The proposed method was successfully applied to the determination of copper in natural water samples. The detection limit (3sigma) was 1.0 mug L-1 for preconcentration at the flow rate 5.0 mL min(-1). The recoveries of spike additions to water samples exceeded 95%.