The results of a series of 29 orthotopic liver transplants in the dog are described. The livers were preserved in a new cold storage fluid, UW solution, and were successfully transplanted after periods of storage of 24, 30, 36, and 48 hr. All six animals transplanted after 24 hr survived beyond 5 days after transplantation and had excellent graft function. Four of six survived for at least 5 days after 30 hr of cold storage, and five of five after 36 hr. Five of six consecutive dogs that received transplants that had been cold-stored for 48 hr survived for 5 or more days. This solution represents a substantial advance over all existing cold storage solutions for liver preservation.