The Colombo Medical School was opened on the 1st of June, 1870. Dr. James Loos became its first Principal. He also taught physiology and principles and practices of medicine. In addition to Dr. Loos, the school had two other teachers; Dr. R. Andree who taught Anatomy and Surgery and Dr. E.L. Koch who taught materia medica and midwifery. The chair in Anatomy was created in 1927. Since then many distinguished men have been appointed to the chair in Anatomy. They were Dr. A. Gordon Smith (1927 - 1929), Dr. W. C. Osman Hill (1930 - 1944), Prof. P.K Chanmugam (1945-1960), Prof. M.J. Waas (1960-1967), Prof. F.L.W. Jayawardene (1967-1975), Prof. P.S.S. Panditharatne (1975 - 1998) and Prof. Rohan W. Jayasekara (1999 - 2015) .
The buildings that made up the school in its early days exist no more. Change has altered the landscape of the School several times in the course of hundred and twenty five years of existence. All that remains of the early landmarks is the Koch Memorial Clock Tower erected in 1881 to perpetuate the memory of Dr. E. L. Koch, the second Principal of the School. The anatomy block which was built mainly in 1913 is the oldest structure of the present buildings which constitute the Colombo Medical School.
From its inception up to 1942, when it acquired university status, the school was a government department. The institution, which began as an "elementary school" in 1870, was elevated to the dignity of a "College" ten years later and remained so until 1942 when the University of Ceylon was established and it was made a faculty of the university. In 1978, the different campuses of the University of Ceylon received independent university status and the School was made the Faculty of Medicine of the University of Colombo.