He died Friday, the Nelson-Berna Funeral Home in Fayetteville told The New York Times, after being diagnosed with leukemia in May.
Harrison carried out around 20,000 abortions over three decades and spoke out forcefully in defense of his practice. In the 1980s, his Fayetteville Women's Clinic was firebombed, picketed, blockaded and vandalized. Death threats became routine.
In articles and interviews he denounced abortion opponents as "right-wing crazies." They called him a murderer, particularly after he offered free abortions to survivors of Hurricane Katrina in 2005.
Harrison said he felt compelled to perform abortions after many doctors in northwest Arkansas abandoned the practice. For decades, he was the only willing doctor in the region.
Harrison admitted that he destroyed life, but denied that he killed babies. His said an embryo was far from a human being with a brain, and the higher moral value was salvaging the future of an often disadvantaged girl or woman.