Abstract Despite the finding that even weakly histo-incompatible parathyroids were usually rejected promptly in transplant sites of rich lymphatic vascularity, parathyroid allografts did seem to enjoy a significant advantage in longevity over skin and heart transplanted across the same barriers in our laboratory [1, 2], sustaining the impression that parathyroid tissue is immunologically privileged. The influence of histocompatibility and transplant site on parathyroid allograft survival was studied in inbred rats. Ag-B compatible grafts survived longer than Ag-B incompatible ones in all transplant sites. However when care was taken to place parathyroid allografts in transplant sites having rich lymphatic drainage, prolongation of survival was minimal and rejection took place within 23 days in almost every instance. In other transplant sites sharing the characteristic of absent or abnormal lymphatic drainage (skin islands, muscle, and possibly testicle), prolonged parathyroid survival was seen in a high percentage of animals. The possibility is advanced that previous reports of inconsistencies in parathyroid allograft survival may be explained on the basis of variation in the lymphatic revascularization of the individual glands in different transplant sites.