Barclays' head of compliance, former Financial Services Authority boss Sir Hector Sants, is to take time off after suffering from stress and exhaustion.
Sir Hector is expected to return to his post next year.
He is the latest top banking executive to be forced to take time off due to stress.
Lloyds Banking Group chief executive Antonio Horta-Osorio was forced to temporarily step away from his role in 2011 for similar reasons.
Sir Hector joined Barclays at the end of 2012, and was charged with direct responsibility for ensuring the bank's 140,000 staff obey the law in the more than 50 countries where it operates.