BACKGROUND: Forceps biopsy, bronchial brushing, and bronchial washing are used in conjuction with bronchoscopy to provide specimens for histologic and cytologic analysis in patients with suspected lung cancer. This study was performed to evaluate how many times brushing should be done and how much fluid should be used during bronchial washing for increasing diagnostic yield, and to evaluate which combination of these procedures gives the highest diagnostic yield. METHODS: Forty patients, with suspected lung cancer, who had bronchoscopically visible lesions were enrolled in this prospective study. During one bronchoscopic examination four forceps biopsies, four bronchial brushings, and bronchial washing were done in all patients. The patients were divided into four groups by the amount of normal saline used for bronchial washing; group I, 10 ml; group II, 20ml; group III 30ml, and group IV, 40ml. We analyzed the results in 36 patients confirmed as lung cancer. RESULTS: The diagnostic sensitivity of bronchial washing before and after forceps biopsy and bronchial brushing were 36% and 28%, respectively. The cumulative diagnostic sensitivity of bronchial washing were 47% and significantly higher than that of bronchial washing before or after forceps biopsy and bronchial brushing (p < 0.05). The diagnostic sensitivity of bronchial washing with saline of 30ml was significantly higher than that of bronchial washing with saline of 10ml or 20ml (p < 0.05). The diagnostic sensitivity of the first brushing was 75%, the second brushing 78%, the third brushing 83%, and the fourth brushing 67%. With repeated brushing up to three times, the diagnostic sensitivity increased to 92% (p<0.05). However, inclusion of the fourth brushing did not give a further increase of the diagnostic sensitivity. The diagnostic sensitivity of forceps biopsy was 86%. The diagnostic sensitivities of forceps biopsy by the type of bronchial lesion were as follows: tumor, 88%; infliltration, 67%; infiltration with nodularity, 80%; and collapse, 100%. The combination of forceps biopsy and bronchial washing gave a diagnostic sensitivity of 89%. The diagnostic sensitivity of combining forceps biopsy with bronchial brushing was 97%. Addition of bronchial washing did not increase the diagnostic yield over forceps biopsy and bronchial brushing. CONCLUSION: In patients with central lung cancer, forceps biopsies and repeated brushings up to three times should be done for maximal diagnostic yield.