Kidney donation by young children and the mentally retarded has been supported by court decisions, arguments based on obligations inherent in family relationships, an array of contextual factors, and the principle of beneficence. These justifications for taking organs from people who cannot protect themselves are problematic and must be weighed against our obligation to protect the vulnerable. A compromise solution is presented that strongly protects young children and the mentally retarded but does not abdicate all responsibility to relieve suffering. Guidelines (...) are proposed that prohibit the retrieval of kidneys from young children and the mentally retarded but permit one exception. They would allow retrieval of a kidney when the consequence to a first order relative with whom the donor has a meaningful and valuable relationship is otherwise imminent death. This would be done in accordance with additional guidelines that minimize harm to the donor. Since most patients with end stage renal disease can be maintained on dialysis the need for a kidney to prevent death should be an uncommon occurrence. This compromise is proposed as a solution to a dilemma that exists because two ethical principles are in conflict and one cannot be honored without violating the other. (shrink)