Hull's appeal against Tom Huddlestone's sending-off at Everton on Saturday has been rejected by the Football Association, the club have announced.
Huddlestone was shown a straight red card by referee Paul Tierney following his challenge on Idrissa Gueye midway through the second half.
The midfielder will therefore serve a three-match suspension, meaning he will miss the Premier League games against West Ham, Middlesbrough and Manchester City.
Hull were trailing 1-0 when Huddlestone was given his marching orders, and went on to lose 4-0.
The FA's decision is a blow to their survival hopes with the Tigers currently lying third from bottom, three points from safety.