In order to diagnose lung cancer at gene level, bronchial biopsy specimens from lung cancer patients, who were diagnosed by pathologic method using biopsy specimens from the same site, were used for detection of p53 gene mutation by polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP)-silver staining method. 15 of 25 (60%) specimens were found to be positive. In 10 small cell lung cancer specimens, 7 were positive; in 15 non-small lung cancer specimens, 8 were positive. These results coincided with those of other reports using surgical specimens and sequencing method. Clinical analysis showed no correlation between SSCP positivity and the patients' clinical data such as age, sex, smoking habit, stage of tumor at the time of diagnosis. It is concluded that a small piece of bronchial biopsy specimen could be used to detect p53 gene mutation instead of surgical specimens and this method might be used as an adjunct to cancer screening or for a gene diagnosis prior to gene therapy. In comparison with the routine radionuclide labelled method, silver staining method has the advantage of being simple, quick, economic, safe and convenient for clinical use.