The former Bihar chief minister, who has been granted a six-week bail by the Jharkhand High Court, reached the Jay Prakash Narayan Airport in Patna on a wheelchair.
He will be accompanied to Mumbai by RJD leader Bhola Yadav.
Mr Prasad (69), who had undergone a bypass surgery a few years ago, has sought an appointment with renowned heart surgeon Ramakant Panda at the Asian Heart Institute, sources close to his family said.
Mr Prasad suffers from many ailments, including high blood pressure and diabetes.
The former Bihar chief minister has been in jail since December 23 last year, after being sentenced in a fodder scam case. He was subsequently convicted and sentenced to jail in two more fodder scam cases.