In this study, the membrane extraction of phenol-4-aminoantipyrine complex with the series of aliphatic alcohols was investigated by monitoring the efficiency of the process. A commercial polysulphone hollow-fiber membrane module was used in all experiments. The effects of feed and extragent stream flow rates, the ratio of feed to extragent volumes, feed concentrations of phenol and 4-aminoantipyrine and ionic strength of the feed on the efficiency of the preconcentration process were investigated. It has been shown that the efficiency of the studied process increases with decreasing the solubility of alcohols in water, but decreases with increasing their viscosity. In the investigated series of alcohols 1-hexanol showed the highest efficiency.