To assess the incidence of multiple primary malignancies combined with lung and other organs Methods All patients who were consecutively treated for lung cancer from December 1964 to December 1992 were retrospectively analyzed regarding the occurrence of simultaneous primary tumor elsewhere in the body Results Of 1019 patients reviewed, 21 (2 1%) had associated carcinoma of other organs In these 21 patients, the incidence of associated aerodigestive tract cancer was 71% and cancer of other organs was 29% Five patients had simultaneous cancer with the lung cancer and 16 metachronous lung cancer associated with cancer of other organs Conclusions Multiple primary tumors in patients with carcinoma of the lung is not a rare phenomenon Surveillance programs for detection of second primary tumors should focus on this group of patients Surgeons should be aware of the possibility of double cancer, and the patient’s condition and stage of the carcinoma must be taken into consideration in the determination of operative indications and method To assess the incidence of multiple primary malignancies combined with lung and other organs Methods All patients who were consecutively treated for lung cancer from December 1964 to December 1992 were retrospectively analyzed regarding the occurrence of simultaneous primary tumor elsewhere in the body Results Of 1019 patients reviewed, 21 (2 1%) had associated carcinoma of other organs in these 21 patients, the incidence of associated aerodigestive tract cancer was 71% and cancer of other organs was 29% Five patients had simultaneous cancer with the lung cancer and 16 metachronous lung cancer and With cancer of other organs concludeds Multiple primary tumors in patients with carcinoma of the lung is not a rare phenomenon Surveillance programs for detection of second primary tumors should focus on the group of patients Surgeons should be aware of the possibility of double cancer, and the patient’s Condition and stage of the carcinoma must be taken into Consideration in the determination of operative indications and method