Fibromyalgia is a pain disorder listed in the International Classification of Diseases (ICD) of the World Health Organization under the code 729.1. It is a controversial disease that affects young people in many cases during their working years, posing a social and labour problem, in addition to the complexity of its diagnosis, which is based almost exclusively on clinical criteria as few objective data can be obtained from physical examination or additional tests. Nowadays, the criteria for clinical diagnosis of fibromyalgia are established and periodically revised by an Expert Consensus Panel; the most recent document is dated May, 2010. The occupational status of these patients attains an important significance due to the labour costs resulting from this disease and the difficulty in establishing clear and concise parameters for assessing the personal disability of the patients by the legally authorized organizations.