Almost any healthy adult between 18 and 60 can potentially donate a portion of their liver to someone who needs a transplant. The liver is the only organ that regenerates, which makes living donation possible: surgeons remove a section of the donor’s liver, and both the donated piece and the remaining portion grow back. Deceased donors, meanwhile, can provide a full liver. Each path has its own set of eligibility requirements.
Age and General Health Requirements
Living liver donors must be between 18 and 55 or 60 years old, depending on the transplant center. Mayo Clinic, for example, sets the upper limit at 60 because the liver does not regenerate as efficiently in older adults. Beyond age, donors need to be in good overall health with no major chronic conditions like uncontrolled diabetes, heart disease, or active infections. You don’t need to be an athlete, but your body has to be healthy enough to handle a major surgery and recover well.
The evaluation process is thorough. Expect blood tests, a complete physical exam, detailed imaging of your liver, a review of your full medical history, and a psychological evaluation. The entire workup can take several weeks.
Blood Type Compatibility
Your blood type needs to be compatible with the recipient’s. Most transplants happen between donors and recipients who share the same blood type or have a compatible one. Blood type O is considered universally compatible and can be used for recipients of any blood group in urgent situations, though this can occasionally cause a complication where immune cells transferred with the graft attack the recipient’s red blood cells.
Rh factor (the positive or negative part of your blood type) is generally not considered in organ matching. While one study linked Rh mismatches to a higher risk of bile duct complications, most transplant centers do not factor it into their decisions.
ABO-incompatible transplants, where donor and recipient blood types would normally conflict, are sometimes performed when no compatible organ is available. This is more common and more successful in children than in adults. When attempted in adults, the recipient typically undergoes treatments before surgery to lower antibody levels and reduce the risk of rejection.
Weight, Liver Fat, and Body Size
Most transplant centers set a BMI cutoff of 30 to 35 for living donors. The concern is not weight itself but what it does to the liver. Obesity is the single most significant risk factor for fatty liver, and a liver with too much fat performs poorly after transplant. Donors whose liver biopsy shows more than 10 to 20 percent fat content are typically excluded.
If you’re above the BMI threshold but your liver imaging shows no significant fat, some centers will still consider you. A recent study found that donors with a BMI of 30 or higher but no detectable liver fat on MRI had successful transplant outcomes, though they faced a higher risk of wound complications after surgery. If your BMI is borderline, a center may ask you to lose weight and return for re-evaluation rather than reject you outright.
Liver Size and Anatomy
The donated portion of liver has to be large enough to sustain the recipient but small enough that the donor retains sufficient liver to function safely. Surgeons use a measurement called the graft-to-recipient weight ratio, with 0.8 percent of the recipient’s body weight considered the standard minimum. When the graft is too small, the recipient faces a significantly higher risk of liver dysfunction: in a multicenter study of undersized grafts, about 37 percent of recipients developed complications tied to insufficient graft volume, and this was linked to higher mortality at 30 days, 90 days, and one year.
On the donor’s side, the remaining liver must be at least 25 percent of the original volume. If imaging shows your anatomy wouldn’t leave enough liver behind, or that removing a sufficient piece for the recipient isn’t feasible, you won’t qualify. Certain anatomical variations also cause problems. If your portal vein branches in an unusual pattern or you have more than three bile ducts that would need to be reconnected, surgeons will likely rule you out because the technical complexity raises the risk for both parties.
Who You Can Donate To
You do not need to be related to the recipient. Living liver donation falls into two categories. Directed donation means you choose a specific person to receive your liver, whether that’s a parent, sibling, child, spouse, friend, or even an acquaintance. Non-directed (anonymous) donation means you volunteer to donate without knowing who will receive the organ. In anonymous donations and paired exchanges, federal regulations require that the identities of donors and recipients remain confidential.
The key legal requirements are the same regardless of your relationship to the recipient: you must be competent to make medical decisions, fully informed about the risks, and free from coercion or financial inducement. No one can pressure you into donating, and the transplant team is specifically trained to screen for that.
The Psychological Evaluation
Every potential living donor goes through a psychosocial assessment. The team evaluates your relationship with the recipient, your readiness to donate, your support system for recovery, and your overall psychological stability. This isn’t a pass/fail personality test. It’s designed to make sure you’re making a voluntary, informed decision and that you have people around you who can help during recovery.
Having a history of mental illness does not automatically disqualify you. In one study of over 100 living liver donors, about 6 percent had a prior diagnosis such as depression, adjustment disorder, or a gambling disorder, but all were in remission at the time of evaluation and were approved. The team also watches for psychological defensiveness, where a donor minimizes concerns or tries to present an unrealistically positive picture. If evaluators sense this, they look more carefully at whether the decision is truly voluntary and whether family dynamics might be influencing the choice.
Deceased Donor Eligibility
Deceased liver donors are typically young, previously healthy individuals who suffered a fatal brain injury from causes like head trauma, a brain bleed, or loss of oxygen to the brain. The organ is evaluated for function and damage before being offered for transplant. Unlike living donation, there is no age cutoff for deceased donors, though younger donors generally produce better outcomes. Anyone can register as an organ donor, and the medical team determines at the time of death whether the liver is suitable.
Risks and Recovery for Living Donors
Living liver donation is major abdominal surgery, and the recovery is real. Most donors spend about a week in the hospital and need six to eight weeks before returning to normal activities. The liver regenerates quickly: it typically reaches about 80 percent of its original size within the first six weeks and grows to roughly 90 percent within a year.
Severe complications are uncommon. A large real-world study found that complications requiring a return to the operating room occurred in about 1.2 percent of donors, and life-threatening complications occurred in 0.12 percent. There were no donor deaths in the study period. Minor complications like pain, fatigue, and temporary digestive issues are more common but generally resolve within a few months.