Organ transplantation is a vital therapy for the treatment of many patients. Due to blood compatibility rules, there has been a pattern in many jurisdictions for differing organ types where recipients of blood type O experience longer waiting times than those of other blood types, partly due to crosstransplantation of too many O organs to compatible donors of other blood types. In response to this, a recent development in some jurisdictions is a change in the rules to insist upon ABO-identical transplantation. The literature review herein enables us to conclude that unrestricted cross-transplantation has not achieved equity of access across all blood groups in any jurisdiction in which the problem has arisen. The present study next shows that ABO identical transplantation cannot achieve equity, either. It then presents a model for restricted cross-transplantation which indicates how comparable waiting times for all blood types could be achieved. Note: the link is to the final draft. The published article is available below.