Eleven long-term (in culture more than 1 yr) cell lines were established from surgical specimens of human TCC. Characterization studies performed on the individual cell lines showed that each 1) demonstrated an abnormal human karyotype, 2) grew in soft agar, 3) exhibited rapid growth and multilayering 4) was free from microbial and HeLa cell contamination, 5) produced tumors in cheek pouches of immunosuppressed Syrian golden hamsters, 6) contained ultrastructural features consistently found in epithelial cells in culture, and 7) could be grown to high cell densities in roller-bottle cultures.