MacDonald takes over as captain from Stuart Hooper
Mike MacDonald has been named as Leeds Carnegie's new captain, while Rob Rawlinson is the new club captain.
United States prop MacDonald, 27, was Leeds' player of the season last season and is the club's most capped player.
"Any time you captain a side it means a lot to you, so it will be a great honour," said MacDonald.
"To take over from Stuart Hooper, who did a fantastic job for the club, is a privilege and I am looking forward to the challenge of this new role."
The prop moved to Headingley from Worcester Warriors in 2006 and has 50 caps for the USA Eagles and played in the 2007 World Cup.
Like a good captain of a ship, Mike will need to draw those qualities from those around him if the team is to be successful
Leeds director of rugby Andy Key
MacDonald has taken over from second row Stuart Hooper, who has moved to Bath.
Leeds director of rugby Andy Key said: "As a player he is well respected by his peers and I know he is looking forward to the challenge the season brings, as are the rest of the players.
"Strong leaders are an important factor for any team and, as Mike has stated, it won't just be him who is required to show leadership skills.
"Like a good captain of a ship, Mike will need to draw those qualities from those around him if the team is to be successful."