We demonstrated the feasibility of detection of p53 gene mutations in bronchial biopsy samples from patients with lung cancer. Following DNA extraction from two to three pieces of bronchial tissue obtained by fiberoptic bronchoscopy, p53 gene mutations were screened using polymerase chain reaction/single-strand conformation polymorphism technique. We examined four bronchial biopsy specimens from patients with squamous cell carcinoma of the lung and detected one point mutation at codon 130 (C to G, Leu to Val). This technique will be very useful for studies on early detection of lung cancers or for an analysis of a suspected premalignant lesion. Furthermore, this technique enables us to know the status of oncogene or tumor suppressor gene at the time of diagnosis, which may be very useful for a treatment of patients with cancer in the not too distant future.