In some ways, medical science has come a long way in a short time when it comes to transplanting human organs. But in one important respect, such life-saving efforts often remain needlessly and tragically thwarted.

In the past 20 years, breakthroughs in surgical techniques, immunosuppressive drugs and tissue typing have translated into increasingly successful transplants of hearts, livers, kidneys, lungs, skin, corneas, bone, bone marrow, adrenal glands, ovaries, blood vessels and cartilage.The big problem, however, is that not enough organs are being made available for such operations even though there are more than enough potential donors. As a result, the worst often happens and people die while waiting for an organ donation that never materializes.

The best potential donors are between the ages of 15 and 65 who were in otherwise good health but died suddenly and were declared "brain dead." Brain death is a condition in which brain function has permanently ceased but the heart and lungs can function with the use of artificial life supports.

This week the St. Petersburg, Fla. Times reported that of the estimated 30,000 brain deaths in the United States each year, only about 14 percent become donors.

Yet, if all brain deaths resulted in organ donation, there would be more than enough vital organs to accommodate all eligible recipients.

Among the groups trying to deal with this challenge is a national organization called the United Network for Organ Sharing. UNOS makes sure there are no special favors in selecting the recipients of a donation. Patients are put on a national waiting list. The hard-and-fast rule is: First come, first served.

For information on how to become an organ donor, call the United Network for Organ Sharing at (800) 24-DONOR.