BACKGROUND: The 3p deletions has been shown to be the most frequent alteration in lung cancers, strongly suggesting the presence of at least one tumor suppressor gene in this chromosomal region. However, no solid candidate for the tumor suppressor gene(s) on 3p has as yet been identified. Recent attention has focused on a candidate 3p14.2 tumor suppressor gene, FHIT, which is located in a .region that is homozygously deleted in multiple tumor cell lines and disrupted by the hereditary renal cell carcinoma t(3;8) chromosomal translocation breakpoint FHIT also spans FRA3B, the most common fragile sites in the human genome. In the present study, we have analyzed expression of the FHIT gene in lung cancer cell lines. METHODS: RNA from 21 lung cancer cell lines (16 NSCLC, 5 SCLC) were extracted using standard procedures. Random-primed, first strand CDNAS were synthesized from total RNA and PCR amplication of coding exons 5 to 9 was performed. The RT-PCR products were electrophoresed in 1.5% ethidium bromide-stained agarose gels. RESULTS: 12 of 21(57%) lung cancer cell lines exhibited absent or aberrant FHIT expression [7 of 16(44%) of non-small cell lung cancer and 5 of 5(100%) of small cell lung cancer cell lines]. CONCLUSION: The result shows that abnormal transcription of the FHIT gene is common in human lung cancer cell lines, especially in small cell lung cancer.