AC Lendrum was born in Midlothian and brought up in Brechin. He was educated at Glasgow High School and Ardrossan Academy then attended Glasgow University from where he graduated MA, MD and BSc. In 1933 he was appointed assistant to Sir Robert Muir at Western Infirmary, Glasgow, and later became a lecturer in pathology at Glasgow University. From 1947 to 1967 Lendrum was professor of pathology at St Andrews University and became professor at Dundee when the University was created there in 1967. Lendrum served on several boards and committees in the University until he retired in 1972. Lendrum was a well respected academic and was visiting professor at Yale in 1960. His experiments with staining tissues, in particular, made a significant contribution to the scientific study of disease. An interest in technical matters led to his honorary membership and presidency of the Institute of Medical Laboratory Sciences. A member of many national and international organisations, he was a Founder Fellow of the Royal College of Pathologists. He was Chairman of the Governors of Duncan of Jordanstone College of Art from 1975-1977.
His first wife, Elizabeth died in 1983. He died at Balla Wray Nursing Home by Windermere on 2 January 1994 at the age of eighty-seven and was survived by his second wife, Dr Ann Sandison.