Bronchoalveolar lavage and subsequent bronchial brushing techniques were examined in 60 consecutive cases of endoscopically non-visible peripheral lung cancer in an attempt to improve the diagnostic rate. Lavaged fluid was processed routinely for cytological examinations, and carcinoembryonic antigen (CEA) concentrations were measured concomitantly. Lavaged fluid gave a cytological diagnosis in 63.3% of the patients. The positive cytology rate by brushing was 76.7% . Of 14 patients with negative cytology on brushing, 6 were positive in lavaged fluid. The combination of bronchoalveolar lavage and subsequent bronchial brushing gave a cytological diagnosis in 86.7% of the patients. CEA concentrations of lavaged fluid of patients with lung cancer were higher than those of patients with non-malignant pulmonary diseases. It may be said that increased CEA concentrations in lavaged fluid suggest lung cancer. The relatively low positive rate (76.7%) by brushing cytology appeared due to a technical problem that the preceding bronchoalveolar lavage made it difficult to accomplish a precise brushing under fluoroscopy. Accordingly, the sequence of the two techniques was reversed thereafter. Of 40 consecutive cases with endoscopically non-visible peripheral lung cancer, brushing cytology gave a diagnosis in 87.5% , and bronchoalveolar lavage did so in 65.0% . The combination of bronchial brushing and subsequent bronchoalveolar lavage gave a cytological diagnosis in 92.5% of the patients. In conclusion, bronchoalveolar lavage was useful in the diagnosis of patients with peripheral lung cancer.