This report confirms reproducible methods to isolate and assess viability and function of pig and human islets. We processed 10 pig and five human pancreata. The pancreata were digested by a modification of Ricordi's automated method for islet isolation. The number of islet equivalents (150 microns diameter islets) was 335,190 +/- 79,345 islets per pig pancreas (5,146 +/- 1,274 islets/g pig pancreas) and 323,630 +/- 147,810 per human pancreas (6,252 +/- 2,572 islets/g human pancreas). The majority of islets were in the range of 50-200 microns diameter, and 20% of the islet population had a size distribution of 200 microns diameter in both porcine and human models. The purity of the final preparations exceeded 90%. The secretory response of perifused islets showed a biphasic insulin release pattern in both species. Perifused fresh pig islets released 2.5 pmol/L islet-1 min-1 at 2.0 mM glucose and 6.2 pmol/L islet-1 min-1 at 16.7 mM glucose. After 7 days culture at 37 degrees C, human islets released 1.32 pmol/L islet-1 min-1 at 2.0 mM and 12.24 pmol/L islet-1 min-1 at 16.7 mM. These results indicate that this procedure is useful to obtain pure, large, and functional islets from pig and human pancreata.