AbstractShort‐term cultures from 12 oral squamous cell carcinomas were cytogenetically investigated. A normal karyotype was found in 3 tumors, 2 of which had many nonclonal changes. Clonal chromosome abnormalities were detected in the remaining 9 cases, in 6 of them in the form of 2 or 3 abnormal clones. In 5 cases the different clones were cytogenetically unrelated, suggesting a multiclonal origin. Numerous additional nonclonal changes were present in 4 of the 9 tumors with clonal aberrations. None of the structural aberrations, clonal or nonclonal, were found in more than one case; nor did any of the rearrangements correspond to cancer‐associated aberrations known from other tumors. The aberration breakpoints of the present series and of a previously reported tongue cancer clustered to bands 1p32, 1p22, 1p11, 1q21, 1q23, 1q25, 1q32, 1q42, 1q44, 2q31, 3p11, 4q35, 7p22, 11p15, 11q13, 12q24, and 17