Gene expression of epidermal growth factor receptor (EGFR), epidermal growth factor (EGF) and transforming growth factor-alpha (TGF alpha) in human colonic carcinoma cell lines (HT10, LST174 and Lovo) was studied by using Northern blot technique. Total RNAs were isolated from these cell lines, separated by 1% agarose gel electrophoresis, transferred onto a membrane and hybridized with EGFR, EGF and TGF alpha probes. EGF and EGFR mRNAs were found in all three cell lines, and TGF alpha mRNA was seen in LST174 and HT10 cell lines but not in Lovo. The results indicate that autocrine stimulation by growth factor exists in human colonic carcinoma cell lines and it may be one of the important causes for the uncontrolled growth of carcinoma cell.