He was 73.
Rangarao, a bachelor, died of a heart related ailment.
According to sources in his family, he went to a hospital last evening and had come back after a check-up, but developed complications and passed away in the wee hours.
He had undergone a cardiac related surgery around 20 years back, sources said.
Rangarao had served as the state education minister when Kotleya Vijay Bhaskar was the chief minister of Andhra Pradesh in the 90s.
He was presently a member of the Andhra Pradesh Legislative Council.