The Global Burden of Disease (GBD) 2000 study, led by the World Health Organization (WHO), updated estimates of the burden of depressive disorders in 2000. Depression was the fourth leading cause of disease burden globally, accounting for 4.4% of total disability-adjusted life years (DALYs) and contributing almost 12% of all years lived with disability (YLDs). These findings highlight the significant non-fatal burden of depression, emphasizing its impact on public health. The GBD 2000 study aimed to improve the comparability, validity, and reliability of epidemiological data for mortality and non-fatal health outcomes. It used new epidemiological estimates and revised disease models, particularly for neuropsychiatric disorders. The study considered depressive episodes lasting 6 months, based on recent research and classical descriptions. Prevalence estimates were derived from published and unpublished studies, with data from the WHO multicountry survey 2000–2001 used to derive ICD depressive episode prevalence. Incidence estimates were calculated using the epidemiologic queuing formula P = I × D, where P is point prevalence, I is incidence density, and D is mean episode duration. The study found that depression is a major public health problem, with varying regional impacts. In high-income countries, depression accounted for 8.9% of total DALYs, while in middle- and low-income countries, it accounted for 4.1%. The study also highlighted the importance of considering both fatal and non-fatal health outcomes in assessing disease burden. Depression, though not causing many deaths, contributes significantly to disability and functional impairment. The GBD 2000 results showed that depression is a leading cause of YLDs, particularly in the Americas, and that its burden varies by gender and region. The study emphasized the need for integrating depression treatment into primary care and for developing effective strategies to reduce episode duration and prevent recurrence. It also noted limitations in the generalizability of survey data and the need for more comprehensive epidemiological data to improve burden estimates. Overall, the GBD 2000 study provided critical insights into the global burden of depression, underscoring the importance of addressing mental health as a public health priority. The findings have informed health policy and planning, highlighting the need for improved mental health care and resource allocation.The Global Burden of Disease (GBD) 2000 study, led by the World Health Organization (WHO), updated estimates of the burden of depressive disorders in 2000. Depression was the fourth leading cause of disease burden globally, accounting for 4.4% of total disability-adjusted life years (DALYs) and contributing almost 12% of all years lived with disability (YLDs). These findings highlight the significant non-fatal burden of depression, emphasizing its impact on public health. The GBD 2000 study aimed to improve the comparability, validity, and reliability of epidemiological data for mortality and non-fatal health outcomes. It used new epidemiological estimates and revised disease models, particularly for neuropsychiatric disorders. The study considered depressive episodes lasting 6 months, based on recent research and classical descriptions. Prevalence estimates were derived from published and unpublished studies, with data from the WHO multicountry survey 2000–2001 used to derive ICD depressive episode prevalence. Incidence estimates were calculated using the epidemiologic queuing formula P = I × D, where P is point prevalence, I is incidence density, and D is mean episode duration. The study found that depression is a major public health problem, with varying regional impacts. In high-income countries, depression accounted for 8.9% of total DALYs, while in middle- and low-income countries, it accounted for 4.1%. The study also highlighted the importance of considering both fatal and non-fatal health outcomes in assessing disease burden. Depression, though not causing many deaths, contributes significantly to disability and functional impairment. The GBD 2000 results showed that depression is a leading cause of YLDs, particularly in the Americas, and that its burden varies by gender and region. The study emphasized the need for integrating depression treatment into primary care and for developing effective strategies to reduce episode duration and prevent recurrence. It also noted limitations in the generalizability of survey data and the need for more comprehensive epidemiological data to improve burden estimates. Overall, the GBD 2000 study provided critical insights into the global burden of depression, underscoring the importance of addressing mental health as a public health priority. The findings have informed health policy and planning, highlighting the need for improved mental health care and resource allocation.