Macleod spent his early years in Achiltibuie and Inverness. He attended the Leachkin Primary School, Jedburgh Grammar School and Loretto School, Musselburgh, before studying medicine at the University of Edinburgh. As an undergraduate he was President of Edinburgh University Students' Association. After graduation, he held a number of junior medical posts in Edinburgh and Forth Valley. He was Rector of the University of Edinburgh from 1994 to 1997, Secretary of the Labour Campaign for a Scottish Parliament, and a member of the National Executive of the Scotland FORward campaign, the cross party group which campaigned for a YES-YES vote in the 1997 devolution referendum.