Hospital sources said Khurana, 77, was brought to the hospital at 3 AM in an unconscious state and there was bleeding inside his brain.
They said doctors performed an operation following which the bleeding has been controlled. Khurana is showing signs of improvement, they added.
He was operated upon by senior neuro surgeons Rajesh Acharya and Sameer Kalra.
Delhi BJP president Vijay Goel and a number of senior city BJP leaders visited Khurana at the hospital.