Background. This article studies multicenter coordination of unspecified living kidney donation and transplantation across the blood-type barrier in kidney exchange. Important questions are whether such coordination should use domino paired donation or nonsimultaneous extended altruistic donor chains, what the length of the segments in such chains should be, when they should be terminated, and how much time should be allowed between matching rounds. Furthermore, it is controversial whether the different modalities should be coordinated centrally or locally and independently. Methods. Kidney exchange policies are simulated using actual data from the Dutch national kidney exchange program. Sensitivity analysis is performed on the composition of the population, the time unspecified and bridge donors wait before donating to the waitlist, the time between matching rounds, and donor renege rates. Results. Central coordination of unspecified donation and transplantation across the blood-type barrier can increase transplants by 10% (P<0.001). Especially highly sensitized and blood type O patients benefit. Sufficient time between matching rounds is essential: three-monthly exchanges result in 31% more transplants than weekly exchanges. Benefits of nonsimultaneous extended altruistic donor chains are limited in case of low numbers of highly sensitized patients and sufficient unspecified donors. Chains are best terminated when no further segment is part of an optimal exchange within 3 months. Conclusions. There is clear synergy in the central coordination of both unspecified donation and transplantation across the blood-type barrier in kidney exchange. The best configuration of a national program depends on the composition of the patientYdonor population. Copyright © 2013 by Lippincott Williams & Wilkins.