An extraction system of ammonium pyrrolidinedithiocarbamate (APDC)-methyl isobutyl ketone (MIBK) was used for a pretreatment in the flameless atomic absorpion spectrophotometric determination of cadmium, lead, and copper. The extract (30μl) was injected into the carbon tube, dried, ashed, and atomized by passing an appropriate current through the atomizer for each step. The concentrations of cadmium, lead, and copper were calculated from the calibration curves by measuring the absorption peak heights at 2288Å, 2170Å, and 3247.5Å, respectively. The sensitivities for 1% absorption were 0.004 ppb for cadmium, 0.045 ppb for lead, and 0.093 ppb for copper. The coefficients of variation (10 replicate samples) were 3.8% for cadmium, 3.4% for lead, and 1.8% for copper. Examinations on interference revealed that most diverse ions which interfered with the determination by direct injection of aqueous sample gave no effect even when present in 1000-fold amount. The method was applied to the analysis of river water and sea water with satisfactory results.