Jogging has grown over the past decade into the largest mass participation sport. It requires no special skills and attracts a variety of people, some with past medical problems, others with just a competitive spirit that may lead to medical or orthopaedic problems. If carried out cautiously and thoughtfully the hazards are few and the sense of well being derived from improved physical fitness is great. The general practitioner, whatever his views on jogging, will be called upon to advise and treat joggers and an awareness of the benefits as well as the hazards is essential.