OBJECTIVE Aspiration of bronchial wash fluid is commonly used in conjunction with brushing and forceps biopsy to diagnose endoscopically visible lung cancer. However, the optimal sequence of these procedures is subject to debate. The objective of this study was to determine if the order in which bronchial washing is performed relative to bronchial brushing and forceps biopsy has any effect on the diagnostic yield. PATIENTS AND METHODS A prospective, cross-sectional study was carried out on patients with endoscopically visible lung cancer who underwent video-assisted fiberoptic bronchoscopy for diagnostic purposes. Aspiration of bronchial wash fluid was performed on all patients both before and after bronchial brushing and forceps biopsy. The results were analyzed separately for each type of endobronchial lesion and for both together. RESULTS The study included 75 patients, with a mean age of 63.3 years; 81% were men. Bronchoscopy was diagnostic in 71 (94.7%) cases. Findings from bronchial washing fluid were positive in 40 (53.3%) patients when washing was performed prior to brushing and forceps biopsy; when washing was performed after these procedures, findings were positive in 43 (57.3%) patients (P=.6). The combined diagnostic yield of washing before and after brushing and forceps biopsy was 69.3%, a significantly better result than either washing before (P=.001) or after (P=.004) the other sampling techniques. In cases where findings from washing done after brushing and forceps biopsy were negative (14 of 32, 43.7%), blood in the aspirated sample interfered with cytology. In comparison, when washing was performed prior to brushing and biopsy, that problem arose in only 3 of the 35 cases (8.5%) (P=.002). CONCLUSIONS The order in which bronchial washing is performed in relation to other sampling techniques for diagnosing bronchial tumors does not influence the diagnostic yield. This is probably because the aspirated fluid sample is more likely to contain excessive blood when washing is performed after brushing and forceps biopsy. However, the diagnostic yield can be significantly increased by combining the findings from bronchial washings performed both before and after other sample collection procedures.