The disability adjusted life year (DALY) concept has been developed as a universal measure of the burden of disease at the country or regional level. The DALY combines years of life lost due to premature death and quality of life lost due to disability to a sum of total lost years of healthy life. First applied in the burden of disease studies conducted in 1990 and 2001, the DALY concept allowed the first international comparison of the burden caused by the most important acute and chronic diseases. Mental disorders were identified in these studies as the most important causes of lost healthy life years worldwide. Meanwhile the DALY concept has been established as basis of effectiveness measures in the international health economic evaluation of health care interventions by the WHO-CHOICE programme. Resulting from the CHOICE studies data on cost-effectiveness of the most important standard interventions for depression, bipolar disorder, schizophrenia and alcohol abuse are available for all WHO regions. In recent studies the DALY concept has been used to predict the consequences of optimizing the mental health care resource allocation on the efficiency of mental health care systems at the national level. Regarding these research activities the DALY concept can be considered as an important methodological tool for mental health services research and the improvement of international mental health care systems.