We studied chromosomal evolution in a newly established cervical cancer cell line, CUMC-3, by sequential cytogenetic analyses of 6th, 55th, 100th and 314th in vitro passages over 5 years. There were some cells with random gain or loss of chromosome at each passage, but several consistent abnormal chromosomes were detected throughout all the passages. The modal numbers of chromosome per cell were triploid range in early 6th passage, but the numbers were increased and stabilized to hypotetraploid range from 55th to 314 passages. The structural aberrations unvaryingly involved in all cells and passages were chromosome 1 (1p- and 1q-), chromosome 3(3p-), chromosome 8 and 10 (isochromosomes of the long arm), chromosome 11(der(11)t(11q;5q)), and chromosome X (Xp-). The marker chromosomes of iso (13q) and iso (17q) were observed only at passage 55 and 100 respectively, but the marker chromosome 20q+ was added at passage 55 and stabilized to passage 314. Other unidentified markers were found in all passages with variability in numbers and morphology. The chromosomal abnormalities observed in this cell line include many oncogene and antioncogene sites, and those of primary cervical cancers reported previously. This sequential cytogenetic study provide another example demonstrating the remarkable karyotypic stability within a heterodiploid cell line with continued passages. And consistent cytogenetic findings make this cell line a good in vitro experimental model system for the study of relationship between specific chromosomal abnormalities and other genetic alternations in carcinogenesis of cervical cancer.