Human islet isolation outcomes were compared between two purification methods; 32 pancreases were processed by conventional Biocoll purification method (SM, standard method) and 132 pancreases by a refined University of Illinois at Chicago UW/Biocoll method (UIC-UB). There was no difference in donor characteristics between the two study groups. The prepurification equivalent islet number was similar between the groups (359,425+/-40,794 equivalent islet number in SM vs. 370,682+/-17,579 in UIC-UB). SM purified islets were mostly collected in only 2 of 12 fractions (68.9% and 36.3% purity). With the UIC-UB, highly purified islets were collected in 6 of 12 separate fractions (fractions 3-8 with purity of 84.8%, 82.5%, 72.0%, 59.3%, 46.8%, and 36.2%). UIC-UB yielded significantly greater islet yield compared with SM (368,419+/-18,245 vs. 260,908+/-37,835, P=0.017). Islet recovery rate was superior in UIC-UB (84.9% vs. 64.5%, P=0.04). Our study demonstrates a superior recovery of highly pure human pancreatic islets after purification using the refined method of UIC-UB gradient.