The ICD-10 offers the possibility of double coding of diagnoses in functional disorders on the one hand, somatoform disorders on the other side. The current S3 guideline for "dealing with patients with non-specific, functional and somatoform physical complaints" states that "[...] in most cases, the specialty of the (initial) examiner and not the clinical constellation seems to define how a diagnosis is made". Based on selective routine data of the Daimler BKK for the years 2008-2010 frequencies of specific functional diagnoses were compared with those of somatoform disorders, additional diagnoses analyzed and compared with epidemiological data from the Federal Health Monitoring System. The incidence found in epidemiological studies of somatoform disorders cannot be found in present routine data. Functional disorders were more frequently diagnosed than somatoform disorders. Certain additional diagnoses that may provide clues to etiological relations are rarely used. As the validity, reliability and purpose of ICD-10 invoicing diagnoses is debatable, there seems to be an imbalance relevant for the health care system. Non-adherence to the guidelines may prevent adequate quality and quantity of patient care.