Using polymerase chain reaction single strand conformation polymorphism analysis (PCR-SSCP), the authors mutations in exon 5, 7 and 8 of the p53 gene in lung cancer tissue from 15 of 36 silicotic patients. Mutations existed in exon 5, exon 7 and exon 8, but occured more frequently in exon 8. The authors also found that p53 gene mutation rate in lung adenocarcinomas of silicotic patients was higher than that of those without silicosis. A single base substitution was found by DNA sequencing analysis in sample C8. As a result, No. 144 codon was mutated from CAG to AAG, so Gln was substituted by Lys. The authors' data suggest that p53 mutation may play an important role in the pathogenesis of lung cancer of silicotic patients.