Meticulous documentation of each patient diagnosis is a particular importance now that we have become so cost-conscious, subservient to quality control and to performance rating in general. This results in substantial arguments in connection with present discussions about which drugs prescribed by the doctor will be paid for by statutory sickness insurance bodies, including for which costs they are willing to reimburse hospitals and patients. So far clinics have been using the International Classification of Diseases ICD-9 as key to diagnosis plus individual diagnostic keys in clinics specifically designed for rehabilitation work. As a matter of fact such individual keys stand in their own right because they are the only on-target tools for the specific performance spectrum of a clinic specialised on subsequent recupation treatment of patients after their discharge from hospital. In a specific clinic of this type in Bavaria with 120 beds, 768 patients were treated in 1996 with 2072 diagnoses. Disease patterns from the orthopaedic and surgical specialist disciplines were particularly frequent among elderly patients and often associated with age-conditioned diseases. Internal medicine accounted for 38% of the individual diagnoses, followed by survey with 25% and by the less extensive specialist areas with 22% including dermatology, allergology, urology, gynaecology, psychiatry, neurology, ENT and oncology. Orthopaedics followed with 22%.