The criteria for early squamous lung cancer remain open to discussion as patients who have been treated for early stage lung cancer, such as T1N0M0, and appear to have been cured clinically may die from recurrent or metastatic tumors. We reviewed the pathological data on 242 surgical patients with squamous lung cancer and found 31 cases (13%) of early lung cancer, included were early lung cancer of the hilar type as a lesion restricted to the bronchial wall without lymph node involvement, and early lung cancer of the peripheral type as a lesion of less than 2 cm and surrounded by visceral pleura but without lymph node involvement. Of 89 patients with hilar-type squamous lung cancer, 17 (19%) had early lung cancer, and 14 (9%) of 153 patients with peripheral-type squamous lung cancer had early lung cancer (p < 0.05). For early lung cancer of the hilar type, all but 1 (94%) were detected using sputum cytologic study and bronchoscopy. For early lung cancer of the peripheral type, all were detected on chest X-ray, but 57% were cytologically proven to be malignant. The 5-year survival rate for patients with early lung cancer, according to this new criteria is 90%; 92% for the hilar type and 88% for the peripheral type. Thus, classification of early squamous lung cancer is pertinent for determining the prognosis and selection of treatment. We emphasize that efforts be made to detect early lung cancer.