A review of chromosomal analyses of human lung carcinomas is presented. Karyotypic studies have revealed multiple cytogenetic changes in most small cell lung carcinomas (SCLCs) and non-small cell lung carcinomas (NSCLCs). In SCLCs, losses from 3p, 5q, 13q, and 17p predominate; double minutes associated with amplification of members of the MYC oncogene family may be common late in disease. In NSCLCs, deletions of 3p, 9p, and 17p, +7, i(5)(p10), and i(8)(q10) often are reported. The recurrent deletions encompass sites of tumor suppressor genes commonly inactivated in lung carcinomas, such as CDKN2 (9p21), RB1 (13q14), and TP53 (17p13). Despite technical advances in cell culture, the rate of successful karyotypic analysis of lung carcinomas has remained low. Alternative molecular cytogenetic methods to assess chromosome changes in lung cancer, particularly comparative genomic hybridization (CGH) analysis, are discussed. Initial CGH studies confirm the existence of many of the karyotypic imbalances identified earlier in lung cancer and have revealed several recurrent abnormalities, such as 10q- in SCLC, that had not been recognized previously. The further application of such molecular cytogenetic approaches should enable investigators to define more precisely the spectrum and clinical implications of chromosome alterations in lung cancer.