A critical review of Nordic literature on fibromyalgia (FMA), undertaken to test the hypothesised inadequacy of the diagnosis, shows the diagnostic criteria to be entirely subjective and arbitrary, and their use to give rise to problems even in controlled studies. Studies have not only shown even small differences in the diagnostic criteria to have profound impact on prevalence figures and to produce apparent fluctuations on the patient population, but also that the prevalence is higher in areas where many cases have already been diagnosed. No common aetiology or pathogenetic mechanism can be identified, and the massive overrepresentation of women remains unexplained. The patient group is characterised by heterogeneity, and no treatment has shown to be specifically beneficial. Papers offering alternative explanations of FMA are concerned with the reasons why FMA is diagnosed, rather than its cause.