A Mexican group reported transplantation of cocultured neonatal porcine islets and Sertoli cells resulting in insulin independence in nonimmunosuppressed type 1 diabetes patients. We have transplanted similar islets alone (naked islets) or cocultured islets with sertoli cells (islet/sertoli cells) into an omental site and other locations of seven nondiabetic, nonimmunosuppressed, nonhuman primates. Porcine endogenous retrovirus was not detected in recipient blood 8 weeks after porcine islet grafts, and porcine C-peptide was detected at a very low level in all animals. Histology examination failed to demonstrate obviously recognizable islets, but in the animals transplanted with islet/Sertoli cells at the omentum site, there were some surviving glucagons, pan-cytokeratin, and inhibin stained cells at 8 weeks.