The global burden and large diagnostic and therapeutic deficits associated with depressive disorders call for intervention programs. The aim of the Nuremberg Alliance against Depression (NAD) is to establish and to assess the effectiveness of a four-level intervention program for improving the care of patients with depression. A 2-year intervention program was performed in Nuremberg (480000 inhabitants) at four levels: training of family doctors and support through different methods; a public relations campaign informing about depression; cooperation with community facilitators (teachers, priests, local media, etc.); and support for self-help activities as well as for high-risk groups. The effects of the 2-year intervention on the number of suicidal acts (completed suicides plus suicide attempts, main outcome criterion) were evaluated with respect to a 1-year baseline and a control region (Wuerzburg, 270,000 inhabitants). Compared to the control region, a reduction in frequency of suicidal acts was observed in Nuremberg during the 2-year intervention (2001 v. 2000: -19.4%; p< or =0.082; 2002 v. 2000: -24%, p< or =0.004). Considering suicide attempts only (secondary outcome criterion), the same effect was found (2001 v. 2000: -18.3%, p< or =0.023; 2002 v. 2000: -26.5%, p<0.001). The reduction was most noticeable for high-risk methods (e.g. hanging, jumping, shooting). Concerning completed suicides, there were no significant differences compared to the control region. The NAD appeared to be effective in reducing suicidality. It provides a concept as well as many methods that are currently being implemented in several other intervention regions in Germany and in other countries.