Thirty-nine canine segmental pancreatic autografts were preserved at 4 degrees C for 48 hr prior to transplantation using five different preservation solutions: modified silica gel-filtered plasma (SGFP) (n = 10); modified PPF (n = 9); modified Collins' solution (n = 8); partially modified plasma protein fraction (PPF) (n = 6), and unmodified PPF (n = 6). These modifications were with respect to osmolality, pH, protein, and potassium content. Graft function was assessed by daily fasting blood sugar and serum amylase, and by intravenous glucose tolerance test (IVGTT) and insulin output at 14-21 days. Viable preservation was deemed successful if normoglycemia was maintained for at least 5 days. Modified SGFP was successful in 80% of the animals, modified PPF in 100%, partially modified PPF in 60%, unmodified PPF in 50% and modified Collins' solution in 37%. The difference between modified PPF and the latter three solutions was significant (P less than 0.05). The causes of graft failure were primary nonfunction, graft pancreatitis, and focal necrosis in some of the grafts preserved by Collins' solution. Graft function in the surviving animals, as determined by the IVGTT and K value, was similar regardless of the method of preservation and was comparable to that previously obtained with fresh and unpreserved segmental pancreatic autografts. It is concluded that modified PPF solution is as effective as modified SGFP in the preservation of pancreatic grafts for 48 hr. The essential elements in this modification appear to be high pH and high oncotic pressure in a hyperosmolar and moderately hyperkalemic solution. Since PPF is readily available and is much cheaper than SGFP, it may be the solution of choice for clinical preservation of pancreas allografts for periods of 24-48 hr.