To celebrate the bicentennial of the 1811 charter to establish the Massachusetts General Hospital, we tell the stories of the physicians and surgeons of the hospital who practiced pathology until the discipline was more firmly established with the recruitment of James Homer Wright who became the first full-time pathologist at the hospital in 1896. One of the two co-founders of the hospital, John Collins Warren (famed primarily for being the surgeon at the first public demonstration of ether anesthesia) had a major interest in pathology; he published a book focused on gross pathology (1837) and began the important specimen collection subsequently known as the Warren Anatomical Museum at Harvard Medical School (HMS). An early physician, John Barnard Swett Jackson, became the first professor of pathology in the United States (1847) and was a noted collector whose specimens were added to the Warren Museum. Dr Jackson showed no interest in microscopy when it became available, but microscopy was promoted from circa the late 1840s at Harvard and likely at the hospital by Oliver Wendell Holmes, the famed essayist who was on the staff of the hospital and faculty at the medical school. Microscopy was probably first used at the Hospital with any frequency on examination of fluids by the first officially designated 'Microscopist,' John Bacon Jr, in 1851, and after the mid-1850s by Calvin Ellis on anatomic specimens; Ellis went on to pioneering reform of the HMS curriculum. Reginald Heber Fitz succeeded Ellis in 1871 and was the first to be officially designated as 'Pathologist' at the hospital. Fitz is remembered for two major contributions: his paper showing the nature of, and potential surgical cure for, the disease that he termed 'appendicitis'; and his description of acute pancreatitis. With the microscope now firmly entrenched and with the increase in surgery after Fitz's work on appendicitis, surgical pathology grew quickly. J Collins Warren, the grandson of the co-founder, had a major interest in pathology and in 1895 published an impressive volume entitled 'Surgical Pathology and Therapeutics.' Dr Warren had a major interest in breast disease and was a pioneer of needle biopsy in the evaluation of breast masses. In 1888, William Fiske Whitney joined the staff of the hospital and spent his nearly 30-year career practicing primarily as a surgical pathologist, making particular innovations in intraoperative consultation. The contributions of these individuals brought the field from a gross pathology-oriented discipline mostly oriented around teaching to a microscopy-dependent practice integral to patient care, and hence set the stage for the formal founding of the Pathology department in 1896.