Chinmayanand was brought to Lucknow and admitted to SGPGIMS on Monday after he complained of chest pain and uneasiness.
According to Prof Amit Agarwal, chief medical superintendent, "Swami Chinmayanand is admitted in the cardiology ward under Prof P. K. Goel, head of cardiology department. His condition is stable but under observation."
Hospital sources said that his blood pressure and all other parameters are normal but doctors wanted to keep him 'under observation'.
A local court in Shahjahanpur had sent Chinmayanand to judicial custody for 14 days on September 20 for sexually assaulting a law student.
He was charged with an offence not amounting to rape, stalking and criminal intimidation.
The law student, who studied in the college run by Chinmayanand, went missing on August 24 after a video of her alleging that a person from 'Sant Samaj' had threatened to kill her and her parents, went viral on the social media.
Later, she testified before a local court that Chinmayanand repeatedly raped her for over a year. She said that the accused recorded the incident on the camera and used it to blackmail her.
Chinmayanand had, in turn, filed an extortion case against the law student and three others.
After she confessed before the special investigating team of having asked for the extortion money to the tune of Rs 5 crore from Chinmayanand, she was arrested and produced before the court, which sent her to 14-days judicial custody, earlier on Wednesday.
The victim's family has alleged that Chinmayanand was using his political clout to stay in hospital.
( With inputs from IANS )