In order to reduce the immunogenicity of parathyroid allografts and induce immunotolerance, we depleted Ⅰa＋ donor cells of rat parathyroid allografts by anti-Ⅰa monoclonal antibody plus complement, transplanted the treated glands underneath the capsule of the recipient kindey,and observed the median survival time (MST) of the allografts. Our results showed that the MST of the treated group were 60 days, compared with control group (MST:14 days), Ｐ＜0.01. This results indicate that rat parathyroid allografts survival can be prolonged dramatically by depletion of Ⅰa＋ donor cells.