A model calculation was used to assess whether the G-DRG version 1.0 sufficiently represents integrated internal psychosomatic treatment of patients with psychosomatic disorders in relation to diagnosis and resource consumption. The DRGs of the Major Diagnostic Category "Mental Diseases" of the German DRG calculation sample 1.0 (diagnoses, procedures, cost weights) were analyzed. In a division of psychosomatic medicine within a general internal department, proceeds regarding 241 patients treated between 01 Jan and 31 Dec 2002, calculated according to the G-DRG version 1.0, were compared to the costs accrued. The G-DRG version 1.0 includes 7 DRGs of psychosomatic disorders in internal medicine (excluding disorders due to substance abuse). Assuming a base rate of € 2,900, the total proceeds of the G-DRG Version 1.0 exceeded the costs (+ € 57,971 /year).