An isolation procedure for large scale isolation of swine islets is described. The results from 15 consecutive isolations are reported. The glands were excised from heart beating animals with no warm ischemia time. The pancreases were digested by a modification of the automated method for human islet isolation. It was possible to separate an average of 690,000 +/- 279,429 islets per pancreas corresponding to 10,360 +/- 4034 islets for gram of pancreas with a volume of 714 +/- 480 mm3. After purification the recovery was 255,000 +/- 32,407 islets corresponding to 4,000 +/- 567 islets per gram of pancreas. Purity of the final preparation was 80-95% islets. Insulin content resulted in an average of 146.8 +/- 78 U before purification and 71 +/- 53 after purification. After transplantation of an aliquot of the final preparation in diabetic nude mice normoglycemia occurred in six mice. 30 days after transplantation nephrectomy of the kidneys bearing the grafts produced a rapid return to the diabetic state in all cases.