Dog and rat animal models have been developed for repeated intravascular administrations to the liver. However, mice have generally been considered too small to use for these models. This study describes the development of mouse models that permit the establishment of liver metastases that can be subsequently treated by repeated injections into the portal venous system. A mini-laparotomy is done to mobilize the spleen and transpose it to a s.c. pocket with its vascular pedicle intact. A suspension of single tumor cells is then inoculated into the portal vein to establish diffuse liver metastases. These tumors may be treated by simple percutaneous injections directly into the s.c. whole spleen reservoir. The ease of injection into the s.c. spleen permits repeated injections into the portal venous system. The usefulness of this model was shown in experiments revealing that multiple portal venous administrations of a replication-conditional, oncolytic herpes simplex virus mutant are more effective than a single portal venous administration. In a modification of this model, the spleen is first split into two, leaving intact the vascular pedicle for each half of the spleen. Tumor cells are inoculated into one hemi-spleen, which is then resected 10 minutes later. The other hemi-spleen is transposed to the s.c. position, thereby permitting subsequent repetitive portal venous injections via percutaneous injections into the s.c. hemi-spleen. These mouse models are useful for a wide range of studies. ©2005 American Association for Cancer Research.