Hepatic-based metabolic disorders are characterized by an enzyme deficiency expressed solely or mainly in the liver. They are divided into cirrhotic or non-cirrhotic metabolic liver diseases (NCMLDs), and most of them can be treated by liver transplantation. Because the livers with NCMLDs are usually structurally and functionally normal, the primary aim of the liver graft is to support the deficient enzymes rather than maintaining liver functions. Hence, we hypothesize that the exchange of partial liver grafts by the technique of auxiliary partial orthotopic liver transplantation (APOLT) between patients with 2 different NCMLDs may be feasible to replace the deficient enzymes in each patient. This hypothesis is based on the following conditions: (i) the patients have no chance of undergoing timely liver transplantation, (ii) the symptoms of each NCMLD may be alleviated after exchanging partial liver grafts, and (iii) each graft is anatomically appropriate for APOLT. In addition, we evaluate it with a focus on selection of cases, designing of graft sizes, and surgical techniques for reciprocal APOLT.