Our recent linkage study of urethane-induced pulmonary adenomas in SMXA RI strains of mouse revealed two host resistance genes, Par1 (chromosome 11) and Par3 (chromosome 12). The map positions of Par1 and Par3 correspond to human 17q11-23 and 14q11-24, based on synteny between mouse and human. In this study, we examined the loss of heterozygosity (LOH) in these two homologous human chromosomal regions in 30 primary lung adenocarcinoma samples with matched normal DNA. Using 15 highly polymorphic markers, two commonly deleted regions were identified on human chromosomes 14 and 17, respectively. At 17q21, nine (53%) of 17 informative tumors showed LOH between D17S588 and D17S518. On the other hand, at 14q11-12, seven (32%) of 22 informative tumors showed LOH at loci between D14S261 and D14S80. Subsequently, we examined 25 squamous cell carcinomas (SQ) and 24 small cell carcinomas (SCC). At 14q11-12, six (38%) of 16 informative SQ and five (42%) of 12 informative SCC showed LOH. In contrast, at 17q11-23, one (7%) of 15 informative SQ and two (14%) of 14 SCC showed LOH. Therefore, the gene on 17q seemed to affect selectively adenocarcinomas, whereas the other gene on 14q, all three types of lung carcinomas. These observations indicate that a comparative genetic analysis provides a promising approach to survey genes involved in multifactorial process of human lung carcinogenesis.