A case of primary pulmonary cryptococcosis with increased serum carcinoembryonic antigen (CEA) (7.0 ng/ml) is presented. The diagnosis was made by transbronchial lung biopsy (TBLB) and no abnormality was found in either gastrointestinal tract or immunity. Immunohistochemical study of the lung specimen showed that CEA was present on the surfaces of alveoli. The level of CEA fell to 0.8 ng/ml after administration of an antimycotic agent (Fluconazole) with simultaneous improvement of the chest radiographic findings. This case indicates that increased serum CEA depends on pulmonary cryptococcosis. TBLB and administration of antimycotic agents, instead of surgical resection, are useful in the diagnosis and treatment of this disease.