AbstractTwo‐hundred and fifty discrete lesions of the lung and mediastinum were sampled by a modified fine‐needle aspiration biopsy (FNAB) technique. Aspirates were collected directly into 15 ml of Saccomanno's fixative, and all preparative work was carried out in the cytopathology laboratory. Only seven aspirates were “insufficient for diagnosis,” giving a productivity rate of 97%. Five insufficient aspirates later proved to be neoplasms. Of the 243 cases with a primary FNAB diagnosis, 21 had insignificant disease, 29 had benign neoplasms or nonneoplastic disease, and 193 had malignant tumors. Most malignancies could be assigned to a specific histologic type by FNAB; those that proved difficult by FNAB were usually difficult on histopathologic examination. There were no false‐positive diagnoses of malignancy and only eight false‐negative results. Of 12 results interpreted as “Suspicious,” 10 proved to be malignant on follow‐up. This modified method has proven to have a low complication rate and to be both highly productive and reliable in the diagnosis of malignant and nonmalignant disease. Diagn Cyto