The former U.S. Bancorp
Grundhofer was chairman of Citi's risk management and finance committee and also was a member of nomination and governance committee, according to the company's 2011 proxy statement.
In a release announcing the departure, Citigroup chairman Richard Parsons said Grundhofer was resigning to dedicate more time to other interests.
Grundhofer joined the board in 2009, and also is a director for Ecolab Inc
A Citigroup spokeswoman declined to comment.
His resignation shrinks the bank's board to 13 members, and it was not immediately clear if he would be replaced on the board.
(Reporting by Joe Rauch; editing by Andre Grenon)