A 67-year old man patient with dispnea, weakness at the right arin and rectal bleeding. was admitted to our hospital with a nodular large mass in the right upper lung field on chest X-ray. Colonoscopy revealed an ulcerove,etan mass in the rectosigmoid region. Colonoscopic biopsy was performed and the histopathological diaposis of a specimen was evaluated as adenocarcinoma. Chest Computed torno.-raphy revealed an 8 cm mass lesion with heterogenous density in the right upper lung field. Transbronchial biopsy of the specimen revealed squarnous cell carcinoma. The patient was diagnosed as synchronous sqUamous cell luno cancer and rectum adenocarcinoma. who was treated with only supportive therapy due to his poor performance status. Complete blood count showed excessive leukocytosis that was evaluated due to paraneoplastic syndrome. He died shortly after diagnosis. Synchronous lung and rectum cancers together with paraneoplastic leukocytosis was rarely reported in the literature.