Thirty intraoperative needle core biopsies of well-functioning pancreas allografts were performed from 2 days to 7 years posttransplantation (mean 15.4 months). Most samples (83.3%) lacked significant inflammation or fibrosis. The five patients who showed features of ongoing low-grade acute rejection experienced premature graft losses due to chronic rejection. There were no complications related to the intraoperative biopsy itself.