A simple and effective homogeneous liquid-liquid extraction method has been used for the simultaneous extraction and preconcentration of cobalt, copper, and nickel after the formation of complex with 4-benzylpiperidinedithiocarbamate potassium salt (K-4-BPDC), and later they were determined by flame atomic absorption spectrometry (FAAS) using (water/tetrabutylammonium ion (TBA(+))/chloroform) as a ternary component system. The phase separation phenomenon occurred by an ion-pair formation of TBA(+) and perchlorate ion. After the optimization of complexation and extraction conditions ([K-4-BPDC] 2.0 x 10(-4) mol l(-1), [TBA(+)] 2.0 x 10(-2) mol l 21, [CHCl3] 60.0 mu l, [ClO4-] 2.0 x 10(-2) mol l(-1) and pH 6.0), a preconcentration factor of 200 was obtained for only 10 ml of the sample. The analytical curves were linear in the range of 20-1500, 15-2000, 35-1600 mu g l(-1) and the limits of detection were 10, 5, and 15 mu g l(-1) for Co2+, Cu2+, and Ni2+, respectively. The proposed method was applied for the extraction and determination of Co2+, Cu2+, and Ni2+ in natural water samples with satisfactory results.