The model for integrated care (IC) of those seriously mentally ill patients insured with the DAK-Gesundheit health insurance and various Betriebskrankenkassen (members of the VAG Mitte) from the regions Berlin, Brandenburg, Lower Saxony and Bremen allows a complex treatment in the outpatient setting which consists of psychiatrists, general practitioners and clinicians, psychiatric nursing, sociotherapy (only in Berlin), internal medicine quality circles, orientation on treatment guidelines and conceptual consensus with the relevant care clinics. The aim of the evaluation is to illustrate the health economic effects of IC.In the period from 2006 to 2010 insured members of the DAK-Gesundheit and other involved health insurance companies with a serious mental illness, a significant impairment of social functioning and the need to be treated to avoid or substitute an in-hospital stay were included in the integrated care. The cost perspective was that of the statutory health insurance companies. For the health economic evaluation, the utilisation of continuous IC over 18 months was compared to the last 18 months prior to the inclusion in IC. The clinical findings were gathered quarterly during the IC using CGI (Clinical Global Impressions) and GAF (Global Assessment of Functioning Scale).A total of 1 364 patients receiving IC in 66 doctor’s practices were documented (of those, 286 had diagnoses of ICD-10 F2, 724 ICD-10 F32-F39). The median age was 48.8 years, 69% were female. 24% had their own source of income, 40% were on the pension, and the rest of the patients were receiving transfer benefits in some form. In 54% of the cases IC was used to avoid an in-hospital stay, in 46% of the cases to substitute an in-hospital stay. The degree of the CGI was 5.5 on average at the time of inclusion and the GAF score was 36.5 on average. The 226 patients with continuous documentation over 18 months were included in the health economic analysis. The number of days spent in hospital was lower during the IC period as compared to the 18 months prior to IV (11.8 vs. 28.6 days, p<0.001), the inpatient costs were lower (5 929±13 837 Euro vs. 2 458±6 940 Euro, p<0.001), the total was not significantly changed (7 777±14 263 Euro vs. 7 321±7 910 Euro, p=0.65). The substantial reduction of inpatient costs was compensated by the additional costs for medication and the costs of the complex outpatient care. Results were comparable for the 2 subgroups of schizophrenic/schizoaffective (n=66, 40.9 vs. 17.9 days, p=0.03; inpatient cost 9 009±15 677 Euro vs. 3 650±8 486 Euro, p=0.02; total expenditures 11 789±15 975 Euro vs. 9 623±9 262 Euro, p=0.33) and unipolar depressive patients (n=90, 29.8 vs. 9.8 days, p=0.006; inpatient cost 5 664±14 921 Euro vs. 1 967±5 276 Euro, p=0.02; total expenditures 7 146±15 164 Euro vs. 6 234±6 292 Euro, p=0.57).The IC was able to considerably reduce the utilisation of inpatient treatment through offering a complex range of services in the outpatient setting and allowed for a weight-shift in a low-threshold comprehensive care structure without an increase in costs from the statutory health insurance companies' perspective. For a detailed description of clinical effects further studies are required.