Vice President Jagdeep Dhankhar was admitted to the All India Institue of Medical Sciences in New Delhi early on Sunday after complaining of uneasiness and chest pain, sources said.
The 73-year-old was taken to the hospital around 2 am.
Dhankhar was admitted to the Critical Care Unit under Dr Rajiv Narang, head of department of cardiology at AIIMS.
He is stable and under observation, a source said, adding a group of doctors is monitoring his condition.
Union Health Minister J P Nadda visited AIIMS to enquire about Dhankhar's condition.