A new simple spectrophotometric method was developed for the determination of Cu(II) at trace levels by using the chromogenic reagent dimethylglyoxime (DMG). The Cu(II)-DMG complex showed an absorption maximum at 280 nm with an average molar absorptivity value of 1.12x10⁴ L mol^-1 cm^-1 at pH 4.5. Results indicated that Cu(II) formed a stable 1:5 complex with DMG. The calibration curve was linear in the range of 0.25-8.0 mg ml^-1, r = 0.9998, with a detection limit of 69 ng ml^-1 and a quantification limit of 211 ng ml^-1. Interference effects of various ions, commonly associated with Cu(II), were investigated and the results confirmed the high selectivity of the developed method. It was successfully applied to the determination of Cu(II) in synthetic copper alloys, certified reference material (NBS SRM 879) and Cu(II)-spiked bottled mineral water. Recovery values for these samples were found as 103.4% and 103.0%, and 98.01%.