Abstarct: A simple and sensitive flow injection-flam atomic absorption spectrometric (FI-FAAS) procedure was developed for the on-line preconcentration and determinatiom of trace leveles of Cr(III (and Cr(V(. A mini-column packed whit a chloromethylated polystyrene functionalized whit N,N-bis(naphthylideneimino)diethylenetriamine (PS-NAPdein) was used for the on-line ennichment of Cr(III (and Cr(VI) from samples at pH=6.7. The Cr(III (was eluted from the mini-colmn using of 1.5M hydrocoloric acid and Cr(VI) was eluted by two sequential elution with mixture of amonium nitrate 2.5M and ammoniac 1.0M. chemical and flow injection variables were optimized for the quantitative preconcentrationand determination of Cr(III (and Cr(VI). Under the optiomum conditions, calibration gragh were linear over the optimum concentration rang of 5.0-60.0 microg/L for Cr(III (and 10.0-180.0 micro-g/L for Cr(VI). The detection limit (DL) value for the preconcentration of 10.0 ml of sample solution were 0.6 micro-g/L and 2.5 micro-g/L for Cr(III (and Cr(VI) respectively. An enrichment factor of 70-fold and 30-fold were obtained for 10.0 ml sample volume of Cr(III (and Cr(VI) respectively. The relative standard deviation for 6 replicate determination of Cr(III (at the 10.0, 20.0, 40.0 level were 3.9%, 2.45%, 2.55% and for Cr(VI) at the 10.0, 40.0, 100.0 level were 4.1%, 2.2%, 0.8% respectively. The effect of the presence of various species commonly associated with real samples was also investigated.The accuraey of the proposed method was demonstrated by analyzing different water samples.