In the United Kingdom, training in aerospace medicine is provided by a range of post-graduate courses at the Royal Air Force Institute of Aviation Medicine. An Introductory Medical Officers' (IMO) course lasts for two weeks and is attended by all RAF doctors within the first few months of their entry to the Service. Its objective is to teach the elements of aviation physiology and medicine that they will need in the care of aircrew at a flying station. Four courses are held each year. A General Aviation Medicine (GAM) course is available to civilian doctors who wish to gain recognition as Authorized Medical Examiners of commercial aircrew, or who merely have an interest in the subject. It runs concurrently with the IMO course, and much of the material is common to both. Greater emphasis is, however, given to clinical teaching and to civil aviation. The GAM course also occupies two weeks of teaching. A course leading to the Diploma in Aviation Medicine is held once each year, and lasts for six months. It is open to all who have at least one year of previous experience, and has been attended by 244 military and civilian doctors from 25 countries. The D Av Med course covers every aspect of aerospace medicine at an advanced level, and its standard is at least as high as that of a M Sc degree. The Diploma is a recognised academic qualification awarded by the Royal College of Physicians. Royal Air Force medical officers receive an extra three weeks of training immediately following the D Av Med course, to educate them in procedures and policies specific to the RAF. This Advanced Course is essentially practical, and those who complete it are designated as Flight Medical Officers. They receive refresher training given at regular intervals thereafter. Aircrew are taught the basic principles of aviation medicine when they attend the RAF Aviation Medicine Training Centre for training in the use of their personal protective equipment assemblies. These courses are specific to the type of aircraft to be flown, and a pilot will undergo at least four during his flying career. Short courses of a specialised nature are also offered to clinical consultants, medical students, senior Air Force officers, nurses and others. It is now recognised in the United Kingdom that aviation medicine is a component of occupational medicine, and the Royal College of Physicians accepts the D Av Med as evidence of formal education in that branch of medicine.(ABSTRACT TRUNCATED AT 400 WORDS)