We previously constructed telomerase-dependent, replication-selective adenoviruses OBP-301 (Telomelysin) and OBP-401 [Telomelysin-green fluorescent protein (GFP); TelomeScan], the replication of which is regulated by the human telomerase reverse transcriptase promoter. By intratumoral injection, these viruses could replicate within the primary tumor and subsequent lymph node metastasis. The aim of the present study was to evaluate the possibility of systemic administration of these telomerase-dependent adenoviruses. We assessed the antitumor efficacy of OBP-301 and the ability of OBP-401 to deliver GFP in hepatocellular carcinoma (HCC) and metastatic colon cancer nude mouse models. We showed that i.v. administration of OBP-301 significantly inhibited colon cancer liver metastases and orthotopically implanted HCC. Further, we showed that OBP-401 could visualize liver metastases by tumor-specific expression of the GFP gene after portal venous or i.v. administration. Thus, systemic administration of these adenoviral vectors should have clinical potential to treat and detect liver metastasis and HCC.