This protocol details the cryopreservation of human islets, as performed by the Alberta Diabetes Institute IsletCore. Human islets cryopreserved using this method have been found to retain viability and function after 20years of cryogenic biobanking.Manning Fox JE, Lyon J, Dai XQ, Wright RC, Hayward J, van de Bunt M, Kin T, Shapiro AMJ, McCarthy MI, Gloyn AL, Ungrin MD, Lakey JR, Kneteman NM, Warnock GL, Korbutt GS, Rajotte RV, MacDonald PE (2015) Human islet function following 20 years of cryogenic biobanking. Diabetologia, 58(7): 1503-1512.