Born in Queen Street, Glasgow, on April 29th, 1791, the son of James Mackenzie, a muslin manufacturer (d1800). He was educated in the Glasgow Grammar School and University, and began to study divinity with the intention of becoming a minister of the Church of Scotland. In 1810 he turned to medicine, attended at the Royal Infirmary, where in 1813 he acted as resident clerk to Dr Richard Miller, obtained the Licence of the Faculty of Physicians and Surgeons of Glasgow in 1815, and spent nearly the whole of the next three years on the Continent under Roux and Orfila in Paris and Beer in Vienna. He came to London in 1818, attended John Abernethy's lectures at St Bartholomew's Hospital, laying himself out to practise in Newman Street, W. Unsuccessful in his application for a demonstratorship, and disappointed in his hope of practice, he returned to Glasgow in 1819. He took the additional qualification of Fellow of the Faculty of Physicians and Surgeons, began general practice, and, though always with a leaning towards ophthalmology, lectured on anatomy, surgery, materia medica, and medical jurisprudence in Anderson's College - the extra-academical school of medicine in Glasgow. In 1824, in conjunction with Dr G C Monteath, he founded the Eye Infirmary, and in 1828 was appointed Waltonian Lecturer in the University of Glasgow "On the Structure, Functions and Diseases of the Eye". In the same year the first volume of the *Glasgow Medical Journal* appeared, with his name as editor on the title-page. He was well qualified for the position, because he wrote well and fluently, with an extensive knowledge of English, French, and German medical literature. It cannot now be told if he was merely editor, or whether the journal was not in reality his own private venture. In 1838 he was appointed Surgeon-Oculist in Scotland to Queen Victoria. He died at Glasgow of angina pectoris on July 30th, 1868, leaving a widow and one son. Mackenzie was one of the surgeons who raised ophthalmic surgery to the high position it now occupies amongst the special branches of medical science. His *Practical Treatise on the Diseases of the Eye* (1830) remained the standard book on its subject until the introduction of the ophthalmoscope in 1851 caused a radical change in the diagnosis and treatment of intra-ocular disease. The book was translated into German in 1832, into French in an unauthorized edition in 1844, and an authorized edition in 1856, whilst a supplement corrected by the author was issued by Messrs Warlomont & Testelin at Brussels in 1866. Four editions appeared in England, the last one being dated 1854. An oil-painting by Sir Daniel MacNee, PRSA, hangs in the Eye Infirmary in Glasgow. It has been engraved by Messrs Maclure & Macdonald, of Glasgow. There is also an oil-painting in the reading-room of the Faculty of Physicians and Surgeons of Glasgow; it is a replica of a painting by Alexander Keith which was in the possession of Mrs Mackenzie. A marble bust by George Ewing is also in the possession of the family. A replica in freestone adorns the gable on the west front of the new Eye Infirmary in Berkeley Street, Glasgow. A lithograph portrait appears in *Memoirs and Portraits of One Hundred Glasgow Men who have Died during the Last Thirty Years* (Glasgow, 1886). Mackenzie's medical library is incorporated with that of the Faculty of Physicians and Surgeons at Glasgow, and his collection of preparations of the eye is preserved in the medical school of St Mungo's College.