A 67-year-old man underwent total resection of the left lung because of adenocarcinoma, with no evidence of extra-thoracic spread of the cancer. On follow-up, metastatic bone disease was documented and chemotherapy (CMT) which included cisplatin, docetaxel, vinorelbine, and topotecan was administered. Six months after completion of CMT, a rise in total serum protein was noted. Bone marrow biopsy revealed the diagnosis of an IgG lambda myeloma. We report a case of a man with adenocarcinoma of the lung who presented multiple myeloma after completion of chemotherapy.