The first step in the isolation of murine epidermal growth factor (EGF) from submaxillary glands was the trace enrichment of the acid-ethanol extract on Sep-pak C18 cartridges using the step elution with ethanol. The fraction eluted by 60% ethanol contained above 75% of EGF. The final purification of EGF was achieved by reverse-phase liquid chromatography on Novapak C18 column in the gradient of acetonitrile. A comparison of the effectiveness of gel filtration (on Bio-gel P-60 column) and trace enrichment (on Sep-pak C18 cartridges) of the appropriate fractions were analyzed by the reverse-phase high-pressure liquid chromatography, which had demonstrated that hydrophobic separation of EGF had a number of advantages. The homogeneous character of EGF was confirmed by the silver staining of gels after disc-electrophoresis and isoelectric focusing (pI 4.8). The pronounced mitogenic effect of EGF on the primary culture of the rat hepatocytes is described.