The in vitro chemosensitivity of 3 human colorectal cancer cell lines and those invasive cells which were repeatedly selected with in vitra matrigel invasion assay to the anticancer agent, 5-FU, was determined using a semiautomated tetrazolium-based colorimetric assay (MTT assay). The IDvalues of control cells of SNU-C1, SNU-CZA, SNU-61 were 2.37+-4.S2ug/ml, 0.85+0.40ug/ml, 23.9+-13.3ug/ml, respectively, and those of invasive cell groups obtained by matrigel invasion assay were 0.37+-0.24ug/ml, 1.37+1.04ug/ml, 40.5+19.1ug/ml. There were no statistically significant differences between the ID,. values of control cell groups, SNU-C1(0), SNU-C2A(0), SNU-61(0) and those of invasive cell groups(p>0.05). This result was considered to be caused by the homogenization of the established cell lines during passage and maintenance cultivation.