Alexander Monro, secundus, younger son of Alexander Monro, primus (1697-1767), was born in Edinburgh on 20 May 1733. He was educated at Mr. Mundell's School in the city, and in 1752 he entered Edinburgh University to pursue medical studies. From 1753, he occasionally lectured for his father who was Professor of Anatomy and Surgery, and in July 1755 he became Joint Professor with his father. In October 1755 he took the degree of Doctor of Medicine, the subject of his dissertation being De Testibus et Semine in variis Animalibus . After graduating he went to London to attend William Hunter's lectures, then visited Paris, Leyden, and Berlin. In 1758 he succeeded his father as Professor of Anatomy at Edinburgh University and the following year he was elected Fellow of the Royal College of Physicians. He became President of that body in 1779. His works included Observations on the structure and functions of the nervous system (1783), Structure and physiology of fishes explained and compared with those of man and other animals (1785), Bursae Mucosae (1788), and The brain, the eye, and the ear (1797). Between 1798 to 1808, Monro shared the Professorship with his son, Alexander Monro, tertius (1773-1859). Monro died on his estate at Craiglockhart, Edinburgh, on 2 October 1817.

The Dictionary of national biography writes that 'In the fifty years he taught at Edinburgh University Monro Secundus became the most influential anatomy professor in the English speaking world'.