OBJECTIVES:  To determine the age- and gender-specific 12-months administrative prevalence rate of psoriasis in Germany, and to explore physician groups involved in the provision of health care services for these patients.  METHODS:  Data for patients with a diagnosis of psoriasis (L40, ICD-10) were extracted from the Nordbaden claims database, covering the complete subpopulation insured by Statutory Health Insurance (2.238 million lives in 2003; for comparison:  total German population insured by SHI in 2003, 70.2 million) in Nordbaden in South-Western Germany (representing 82% of the total regional population).  Physician groups involved in health care provision were identified.  RESULTS:  44,735 patients with a diagnosis of psoriasis were identified in Nordbaden, corresponding to an overall administrative prevalence rate of 2.0% (95% confidence interval [CI], 1.98-2.02%; no difference between males and females).  Prevalence increased with age (<20 years [y], 0.56%; 20y-<40y, 1.58%; 40y-<60y, 2.62%; 60y-<80y, 3.09%), except for individuals age 80y or older (2.41%).  In the age group 20y-<40y, females were more often affected than males (1.68% versus 1.48%), whereas in the age groups 40y-<60y and 60y-<80y, prevalence rates were higher for males (3.37% versus 2.87% and 2.98% versus 2.21%, respectively).  Most diagnoses were reported by dermatologists (55.0% of patients), general practitioners (46.4%) and specialists for internal medicine (18.0%; figures include patients diagnosed by more than one physician).  Each of the other physician groups included in the study contributed less than 2% of diagnoses.  CONCLUSIONS:  To the best of your knowledge, this analysis provides for the first time administrative data on the prevalence of psoriasis in a German population.  Its findings appear consistent with international studies as well as with reports on the age of onset of psoriasis.  The data may provide a basis for future studies on health care utilization and cost of illness associated with psoriasis in Germany.