The 44-year-old, who works as Tottenham's under-23s coach, was treated by medical staff before being taken away by ambulance.
"We can confirm that Ugo Ehiogu is currently in hospital after collapsing at our training centre earlier today," the Premier League club said in a statement.
"He received immediate treatment on site from our medical staff before being transferred to hospital by ambulance.
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"Everyone at the club sends their best wishes to Ugo and his family. We shall continue to provide updates when we have further information."
Ehiogu, who spent most of his career at Aston Villa where he won the League Cup in 1996, gained four England caps.
As well as playing more than 300 times for Villa, London-born Ehiogu played more than 100 times for Middlesbrough after signing for them in 2000.
He joined Tottenham's coaching staff in 2014.
Tottenham's first-team players were training at the Enfield centre on Thursday ahead of Saturday's FA Cup semi-final against Chelsea although it is unclear whether any witnessed the incident.
(Reporting by Martyn Herman, editing by Neil Robinson)
