GPs and rheumatologists are increasingly consulted about real symptoms for which it is difficult to find any diagnosis other than fibromyalgia, a syndrome that affects a significant proportion of the population. It is characterised by diffuse or localised pains which are always persistent and hard to treat. These pains may be triggered by physical or psychological trauma and exacerbated by stress, inactivity and changes in the weather. It has become so prevalent over the last thirty years that it deserves to be called a “modern disease”. In 1992, the World Health Organisation (WHO) recognised this condition as rheumatic. A survey of 89 Canadian rheumatologists was carried out to ascertain the proportion of patient consultations for fibromyalgia in relation to other rheumatic conditions. This showed that fibromyalgia was the third most common diagnosis, just after arthritis and rheumatoid polyarthritis. Doctors are still debating whether its origin is physical or psychological (see box). However, this is not really the issue: the very real suffering caused by fibromyalgia compels the medical world to continually add to the list of symptoms, discover its causes and identify treatments. And whether it is known as a “syndrome” or a “disease” does not stop it from gaining ground in modern society.