We studied, clinicopathologically, 34 cases of adenosquamous carcinoma (ASC) treated in our institution over the last 30 years. Its incidence was 2.3% of all primary lung cancers. Following findings were characteristics to this type of lung cancer, male dominant, old age, heavy smoker, comparatively large diameter, peripheral location, and normal level of tumor makers. The 5-year survival rates were 35.0% for ASC, 38.1% for squamous cell carcinoma (SCC), and 50.2% for adenocarcinoma (AC). The component of SCC was predominant or equal to that of AC in 27 (79.4%) ASC cases. The degree of cell differentiation was moderate and both SCC and AC components showed the same degree of cell differentiation in most cases. Lymph node metastasis was seen in 15 (48.4%) cases.