Two cases of primary lymphoma of the lung are reported, both of which were misdiagnosed preoperatively as bronchogenic carcinoma before undergoing successful resection. Accurate diagnosis was obtained after operation. These two patients were in good condition after a short period of follow-up. A discussion is presented concerning diagnosis, treatment and prognosis. Also, we point out the reason why so few primary lymphomas of the lung are reported: the mass of the lymphoma is typically so large that surgeons may consider it to be lung cancer in a late stage and thus abandon surgical intervention, or it may be erroneously diagnosed pathologically as undifferentiated small cell carcinoma of the lung.