In this issue ofHeart we publish the guidelines on the management of unstable angina, which have been written jointly by the Royal College of Physicians and the British Cardiac Society.1 They follow quite closely on the heels of the US guidelines on the same subject.2 However, they take a somewhat different approach. The US guidelines are long (nearly 100 pages), exhaustive, and rather cumbersome, although very informative. The British guidelines are much briefer (10 pages), more user friendly, and to the point. Both will be useful to the physician and cardiologist, but the British ones are better value for the time expended reading them!  Another set of guidelines, however useful and informative, raises the issue of the place and authority of guidelines. They should be exactly what they say they are—guidance. However, increasingly in the current nervous medical atmosphere, their observance is being interpreted as mandatory. The quality of medicine, and therefore patient care, will suffer if treatment is based only upon guidelines, and these guidelines are not interpreted and adjusted in the light of the physician's experience of both the condition and the patient. Latitude to deviate thoughtfully from the guidelines must be preserved. It is particularly important since the so called “evidence base” upon which such “evidence based” guidelines are produced is frequently flawed and/or incomplete when examined closely.  The potential danger and misuse of guidelines is emphasised by the very real possibility that commercial companies, whose products are recommended by the guidelines, will use their own interpretation of the guidelines to pressurise physicians into using their products.  Thus, although guidelines are extremely important, they must remain guidelines otherwise medicine will sink into a state where it is practised by rote and not by intelligent thought.