Three out of four donations are made via a nonsurgical technique doctors call PBSC, for peripheral blood stem cell donation. In this technique, blood-forming cells are removed from the donor's blood via a needle stuck in the arm.

The donor must get injections of a drug called filgrastim in the five days leading up to PBSC. It can cause headaches, joint pain, and fatigue. But that's about it as far as discomfort goes.

Marrow donors only give up liquid marrow, taken from the pelvic bone. No bones or pieces of bone are removed.

In the roughly 25 percent of cases in which surgery is required, the procedure is done in the hospital under general anesthesia. The patient is unconscious and feels no pain as doctors use a needle to withdraw liquid marrow from the back of the pelvic bone.

Patients generally go home the same day and are back to their usual routines within a week.

Every medical procedure involves some risk, and bone marrow donation is no exception. But no more than five percent of the donor's marrow is harvested - not enough to cause any problems. The cells replace themselves in four to six weeks.

Donors don't pay to donate. The National Marrow Donor Program takes care of the donor's travel costs - and reimburses other costs on a case-by-case basis.

Each year, more than 10,000 Americans are diagnosed with life-threatening conditions like leukemia or lymphoma. For many of these patients, the only hope of a cure is a transplant from a donor. The need for donors is increasing - especially those from racially and ethnically diverse communities, according to the National Bone Marrow Donor Program.

Most patients who need a marrow transplant do not have a matching donor in the family. These patients depend on unrelated donors.