Aruna Shanbaug suffered brain damage and was in a vegetative state after she was raped and strangled by a hospital worker in 1973.
Pravin Bangar, medical superintendent at Mumbai's King Edward Memorial Hospital, said Shanbaug had been diagnosed with pneumonia and had been on a life support system for the past few days.
Shanbaug's case sparked a debate over India's euthanasia laws after a Mumbai lawyer petitioned the courts to stop force-feeding her through a tube so her suffering would not be prolonged.
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The case was opposed by nurses at the hospital who took turns taking care of her for more than four decades.
