A couple in their 30s stripped in front of Rashtrapati Bhavan on Monday after they were denied entry to the president's house, police said.
The couple went to the main gate of Rashtrapati Bhavan and demanded a meeting with President Pranab Mukherjee.
When security personnel asked for a reason, they didn't respond.
"The couple then took off their clothes," a police officer said.
Stunned security personnel immediately tried to force the couple to wear some clothes, but the man again took off the dhoti he was made to wear and started running down Raisina Hill stark naked, with policemen in hot pursuit.
The man was overtaken by a police jeep and forced inside. The couple was taken to the Parliament street police station.
Police said they failed to tell the exact reason for their 'naked' protest.
The two were behaving abnormally and were taken to the Ram Manohar Lohia hospital for a medical checkup, a police officer said.
They were also produced before a sub-divisional magistrate and later admitted to the Institute of Human Behaviour and Allied Sciences in east Delhi, the officer added.