LA JOLLA, Calif. (AP) _ Dr. Jonas Salk left a legacy of hope and health when he delivered the world from polio's crippling rampage and later tried to devise a treatment for AIDS.

He spent a lifetime stubbornly pursuing his ideas _ first for a polio vaccine and later for a vaccine-like AIDS treatment _ even when they drew skepticism from other researchers.

``There have to be people who are ahead of their time,'' Salk once said. ``And that is my fate.''

Salk died Friday of heart failure at Green Hospital of Scripps Clinic in La Jolla, said Anita Weld, a spokeswoman for the Salk Institute. He was 80.

He had been hospitalized earlier in the day complaining of shortness of breath.

Working at the University of Pittsburgh in the 1950s, Salk became a hero to millions of Americans when he ignored scientific doubters and used killed virus to develop the first polio vaccine.

``The victory of this medical pioneer over a dreaded disease continues to touch many _ from the students who study his work to the countless individuals whose lives have been saved by his efforts,'' President Clinton said in a statement issued by the White House.

Friends described Salk as a visionary.

``He wanted to know everything about everything,'' said Bill Nelson, president of the Scripps Institutions of Medicine and Science in San Diego. ``If you brought something up, you'd better be ready to produce all the data about it.''

During the first half of the 20th century, epidemics of paralytic poliomyelitis swept the United States repeatedly. Polio viruses infected thousands of Americans annually, including President Franklin D. Roosevelt. The viruses caused widespread fear, killing some young victims and condemning many others to iron lungs, leg braces and years of rehabilitation.

The nation's worst polio epidemic was in 1952. The next year, Salk announced development of an experimental vaccine.

Salk and his family were among the first to receive injections. In 1954, more than 1.8 million school children _ nicknamed Polio Pioneers _ participated in a nationwide test of the vaccine during history's largest medical experiment.

The injectable vaccine was declared effective in 1955, and polio's toll plunged. ``What had the most profound effect was the freedom from fear,'' Salk said as he prepared to celebrate the 40th anniversary of the announcement on April 12.

Salk's name became a household word, splashed across magazine covers and newspaper front pages.

In 1990, Life magazine declared polio as ``the AIDS of the '50s.''

``And then ... one man delivered us.''

Because of Salk's vaccine, ``a generation learned to view health as a birthright, assuming that doctors could provide a cure for any ailment if it were attacked with enough boldness and enough money,'' Jane S. Smith wrote in a magazine adaptation of her book, ``Patenting the Sun: Polio, the Salk Vaccine and the Children of the Baby Boom.''

Dr. Albert Sabin's live-virus vaccine _ swallowed on a sugar cube _ was approved in 1961. Many experts believe it is more effective, and it ultimately gained favor, although Salk's vaccine is still used.

Sabin's vaccine carries a minute risk of causing polio, and produces the only known U.S. polio cases today.

Salk said his vaccine was safer. But only weeks after it was declared effective, officials discovered one manufacturer produced some vaccine tainted by live polio virus that infected 204 people, paralyzing three-quarters and killing 11. The government ordered manufacturers to filter the vaccine, a step Salk said reduced its effectiveness.

In 1960, Salk established The Salk Institute in La Jolla, a San Diego suburb. The institute became a leading biomedical research center.

Salk conducted research on multiple sclerosis and cancer before retiring from his own laboratory in 1984. He continued to maintain offices at the institute and, in 1987, co-founded Immune Response Corp. in Carlsbad to search for an AIDS vaccine.

The vaccine really was a treatment to prevent or delay development of AIDS symptoms in people already infected. Salk also hoped to eventually develop a true vaccine to prevent uninfected people from contracting the deadly virus.

Again, there were doubters. Salk modeled his AIDS vaccine after his polio vaccine, using killed AIDS virus. Skeptics argued the approach wouldn't work or carried a risk of making patients develop AIDS symptoms.

Early tests seemed to support Salk's approach, although years of research were expected before its effectiveness could be established or disproved.

``My own view is we will overcome,'' he said earlier this year. ``I am a perennial optimist. We certainly have the knowledge. The question is whether we have the wisdom.''

Salk won many awards, but many scientists considered his contribution overrated. The only Nobel Prize for polio research went to Harvard virologist John Enders and colleagues who made vaccine development possible by showing the polio virus could be grown in culture.

Jonas Edward Salk was born in New York City on Oct. 28, 1914, the oldest of three sons of a garment industry worker.

He earned an undergraduate degree at City College of New York in 1934 and a medical degree at New York University in 1939.

He married Donna Lindsay the same year. They had three sons, but were divorced in 1968. In 1970, he married painter Francoise Gilot, a longtime companion of the late Picasso.

After a 1939-1940 internship at New York's Mount Sinai Hospital, Salk took his first research position at the University of Michigan, where he helped develop flu vaccines.

Salk moved to the University of Pittsburgh School of Medicine in 1947, and two years later became director of the virus research laboratory, where he searched for a polio vaccine.

In recent decades, Salk published three books of his philosophy: ``Man Unfolding'' in 1972, ``The Survival of the Wisest'' with his son Jonathon in 1973 and ``Anatomy of Reality'' in 1983.

Salk is survived by son Jonathon, his wife, and sons Peter and Darrell.