To assess the value of cytologic examination of expectorated sputum in the diagnosis and management of patients with suspected lung cancer.Retrospective chart review.Inpatient wards, tertiary care university hospital.The charts of 357 patients were reviewed. Two hundred eighty-eight of the 357 patients had had initial sputum cytologic examination prior to other diagnostic procedures, of which 41 (15%) had positive cytologic results. Thirty-six of the 41 were confirmed histologically or shown to have metastatic spread by noninvasive tests. Of the 222 patients with negative or unsatisfactory sputum tests, 97 went on to bronchoscopy and 35 had needle-aspiration biopsies. In the population of patients whose chest x-rays were highly suggestive of primary or metastatic lung cancer, the positive rate for cytologic examination was 38/94 (40%). There was no false-positive test in this study. Of the 50 patients with positive cytologic results, five (10%) had diseases that were of a different cell type; two of these five (40%) had diseases that involved small-cell cancer. There was an unsatisfactory delay in obtaining these samples for analysis.Sputum cytology was found to be too insensitive and insufficiently accurate to be included in the routine workup of a patient suspected of having lung cancer. The results of the test did not influence further diagnostic procedures. This test should, therefore, be reserved for patients considered on initial assessment to be too sick for further investigations and treatment.