Cloud point methodology was successfully employed for preconcentration of trace copper, zinc, iron, and nickel prior to their determination by flame atomic absorption spectrometry (FAAS). The metals react with 2-phenyl-1H-benzo[d] imidazole (PHBI) in a surfactant Triton X-114 medium. The effects of analytical parameters including pH, amounts of reagents etc. were investigated on the recoveries of analytes. No influences were observed from the matrix ions. The detection limits (3SDb/m) of 1.8, 2.8, 1.4, and 2.1ng mL-1 for Cu2+, Fe3+, Zn2+, and Ni2+, respectively. The method was applied to metal determination in various real samples. The validation of the procedure was carried out by analysis of a certified reference biological material, BCR 185 R liver samples.