Keith Vaz will be staying in hospital overnight after passing out in his office.
The embattled Europe Minister will remain in Guy's and St Thomas' Hospital in central London under observation.
A spokeswoman at the Foreign Office said he will definitely spend the night in hospital, but it's unclear how long he'll remain there.
He fainted at around 4.15pm during a TV interview in his office with a satellite channel.
He complained of chest pains two weeks ago and had to seek treatment. Tests showed there was no heart trouble.
Mr Vaz has been under intense pressure since the report by the Commons Standards and Privileges Committee into alleged breaches of Commons rules.
Although he was cleared of all but one complaint, he was criticised for failing to co-operate with the inquiry by the Parliamentary Commissioner for Standards, Elizabeth Filkin.
Tories demanded his resignation.
Ms Filkin has written to Tory shadow Cabinet Office minister Andrew Lansley to tell him that a new investigation into links between Mr Vaz and the billionaire Hinduja brothers is under way, it emerged last week.
He received a further setback this week when he was criticised by the Labour-dominated Foreign Affairs Committee over his failure to grasp the details of Britain's Balkans policy.