The Global Burden of Disease (GBD) study, launched by the World Health Organization (WHO) in the 1990s, aimed to provide comprehensive measures of disease burden, including non-fatal health outcomes, to inform global health policy and planning. The study found that unipolar depressive disorders were the fourth leading cause of disease burden in 1990, accounting for 3.7% of total disability-adjusted life years (DALYs). For the year 2000, the GBD 2000 study updated these estimates, finding that depression is the fourth leading cause of disease burden, accounting for 4.4% of total DALYs, and causing the largest amount of non-fatal burden, representing 12% of all years lived with disability worldwide. The study used new epidemiological estimates of mortality, prevalence, incidence, average age at onset, duration, and disability severity to calculate DALYs for depressive disorders in each world region. The results highlight the significant public health problem posed by depression, emphasizing the need for effective interventions to reduce its burden. The study also noted regional variations, with higher burdens in developing countries compared to high-income countries. The findings have important implications for policy-making, planning, and program implementation in mental health care.The Global Burden of Disease (GBD) study, launched by the World Health Organization (WHO) in the 1990s, aimed to provide comprehensive measures of disease burden, including non-fatal health outcomes, to inform global health policy and planning. The study found that unipolar depressive disorders were the fourth leading cause of disease burden in 1990, accounting for 3.7% of total disability-adjusted life years (DALYs). For the year 2000, the GBD 2000 study updated these estimates, finding that depression is the fourth leading cause of disease burden, accounting for 4.4% of total DALYs, and causing the largest amount of non-fatal burden, representing 12% of all years lived with disability worldwide. The study used new epidemiological estimates of mortality, prevalence, incidence, average age at onset, duration, and disability severity to calculate DALYs for depressive disorders in each world region. The results highlight the significant public health problem posed by depression, emphasizing the need for effective interventions to reduce its burden. The study also noted regional variations, with higher burdens in developing countries compared to high-income countries. The findings have important implications for policy-making, planning, and program implementation in mental health care.