Introduction: In order to increase the resectability of patients affected by colorectal cancer liver metastases, the development of hypertrophying techniques of the liver remnant plays an essential role in today's liver surgical techniques. Different experimental models have been developed to understand and precede the behavior of liver regeneration. The purpose of our study is to compare the anatomical-clinical characteristics of 2 of the different ALPPS animal models: the rat and the sheep. Methods: For the study we used 5 sheeps and 5 rats. Due to variability of the sheep liver anatomy, the transection plane was preoperatively evaluated by MDCT. Sheep and rat liver transections were performed and finally we evaluated the feasibility of the technique and volume and weight of ligated lobes and liver remnants. Results: Regarding feasibility, the creation of an ALPPS model in rats seems simple since the middle lobe is eligible for liver transection and the creation of the FLR. Otherwise, in the sheep, the early branching of the right portal and the extension of the drainage of the VHM may condition the viability of the model. After careful performing liver transection, viable future remnant liver volumes represented 20.6%- 36 % (189.8-341.64 gr) of the total liver volume in sheeps. In rats, the average weight of ligated lobes was 9.4±0.40 gr, which represents 78.72% of total liver weight. Conclusions: Although both experimental models are potentially good models for the study of liver regeneration in ALPPS, the sheep model presents limitations in vascular anatomy conditioning its viability.