Today, the long white laboratory coat is an international symbol of the biomedical community. A century ago, the medical service changed drastically when leading physicians were expected to be both researchers and scientists. White coats were adopted to emphasize cleanliness and professionalism. The white coat was first worn by a new generation of physician-scientists.
The scientific revolution in medicine was a founding principle of the Johns Hopkins Hospital. William Welch, the first Chief of Pathology at the Johns Hopkins Hospital, insisted that his trainees follow the scientific method in their research. At the same time, Sir William Osler, the first Physician-in-Chief, emphasized cleanliness in his historic textbook The Principles and Practice of Medicine.