As with all human endeavors, medical care in any setting has observable and occult benefits and risks. The methods of study of these facets of medical care have become known as “clinical epidmiology.”

This article is the introduction to a new series entitled “Topics in Clinical Epidemiology.” The authors are practicing clinicians, one as director of the Quality Assurance department and the other as director of the Hospital Epidemiology department, both at a large tertiary teaching hospital. The series will attempt, in the fashion of the old shoe leather epidemiologist, to reflect those problems and interactions which are the realities of our current practice milieu and experience. That this collection of manuscripts will be presented in an infection control periodical reflects the journal's and the authors' perspective that the same epidemiological techniques that have made infection control clinically successful and cost-effective can be used to reduce noninfectious hazards of medical care, and to enhance the diagnostic and therapeutic benefits of modern medical management.