By 1822 he was physician to the Westminster General Dispensary, to the Infirmary for Children, and to the Scottish Hospital in London.
He was admitted a licentiate of the College of Physicians on 22 December 1821, and a fellow on 9 July 1836.
On 13 Feb. 1833 he was elected physician to St. George's Hospital, and resigned that office in consequence of ill-health in 1845.
Macleod became in July 1822 editor and proprietor of the London 'Medical and Physical Journal,' which had been previously issued under the title of the 'Medical and Physical Journal,' Though the times were stormy for advocates of medical reform, Macleod conducted the paper with tact and ability.
In 1842 he published, with large additions, his Gulstonian lectures 'On Rheumatism in its various forms, and on the Affections of Internal Organs, more especially the Heart and Brain, to which it gives rise,' 8vo, London.