Sputum cytology is an important step in the early diagnosis of roentgenographically occult lung cancer. It identifies primarily intraepithelial lesions, which are the most common squamous carcinomas not detected by helical CT. Patients at highest risk for lung cancer (eg, heavy smokers with airflow obstruction) should undergo sputum cytology. Patients with premalignant lesions (eg, moderate or severe dysplasia) and of course patients with carcinoma in situ or invasive carcinoma should receive fiberoptic bronchoscopy. The diagnosis and treatment of early-stage lung cancer usually has a favorable outcome. Today we have the knowledge and technology that can change the outcome of lung cancer through early identification, particularly in high-risk patients.