Born at Peterville in Kings County, Prince Edward Island, McIntyre's paternal grandfather came to Canada from Scotland around 1785 and settled at Cable Head, PEI. McIntyre's great-grandfather on his mother's side fought under General Wolfe at the Battle of the Plains of Abraham in 1759.
McIntyre was educated at the Quebec Seminary, Laval University and McGill University where he earned his medical degree in 1867. He returned to Prince Edward Island to begin his practice. He served as Kings County coroner for several years.
Following Prince Edward Island's entry into Canadian confederation which occurred, in part, as a result of the debt incurred by the colony for the railway's construction, McIntyre was elected in the 1874 federal election to the House of Commons of Canada as a Liberal Member of Parliament for Kings County. He was defeated in the 1878 federal election but regained his seat in 1882 and was re-elected in 1887. After being defeated in the next two elections, McIntyre was appointed the seventh Lieutenant Governor of Prince Edward Island by the Laurier government in 1899. He served in office until 1904 and died six years later in Souris, P.E.I.
- Prince Edward Island:Lieutenant Governors Gallery:Peter Adolphus McIntyre, Government of Prince Edward Island, accessed December 26, 2007
- Peter Adolphus McIntyre – Parliament of Canada biography