We established patient-like models of lung cancer metastasis by orthotopically implanting human non-small cell lung cancer cell lines into SCID mice. We evaluated the utilities of small-animal computed tomography (CT) and positron-emission tomography-computed tomography (PET/CT) in these models to non-invasively and repeatedly monitor the anticancer effects of cisplatin and erlotinib. We orthotopically implanted three non-small cell lung cancer cell lines, A549, FT821 and PC-9, into SCID mice. These mice were then divided into three groups: Control, cis-diamminedichloroplatinum (II) (CDDP) (7-mg/kg CDDP, single administration intraperitoneally), and erlotinib (25 mg/kg erlotinib/day, oral administration 5 days/week). After treatment initiation, we repeatedly performed PET/CT and CT measurements and assessed anticancer effects based on tumor volumes and FDG uptake. A549 tumors were not affected by CDDP or erlotinib. FT821 tumors were highly responsive to CDDP. PC-9 tumors, which have an epidermal growth factor receptor mutation, were highly responsive to erlotinib. Histological results and metastatic rates correlated with the anticancer effects shown by CT. In our orthotopic SCID mouse lung cancer models, 18FDG-PET/CT and CT imaging non-invasively and repeatedly monitored the efficacies of cisplatin and erlotinib against not only implanted tumors, but also mediastinal lymph node metastases.