The incident took place when Puneet Sharma was walking down the stairs after having his dinner at Parikrama restaurant, located at 16th floor of a building in Connaught Place late last night, they said.
His friends told the police that he probably slipped and fell down.
He was rushed to Fortis hospital where his condition is stated to be critical, police said.
Sharma had recently completed his MBBS from Ukraine and had come to the restaurant to have dinner with his friends.