The contribution of mental disorders to the Global Burden of Diseases (GBD) Study is now well recognized – mental disorders account for 6.8% of the total burden worldwide. Because the GBD’s health metric Disability-Adjusted Life Year (DALY) combines the impact of both morbidity (Years Lived with Disability; YLDs) and mortality (Years of Life Lost; YLLs), it has foregrounded the previously neglected contribution of mental disorders to the global disease burden. However, this health metric does not account for comorbidity adequately, which leads to an underestimation of excess morbidity and mortality associated with mental disorders. This bias has serious implications for service planning and resource allocation. The focus of FundaMentalHM is to use aggregated data from the GBD Study and register-based individual-level data from the whole Danish population to fill the existing methodological gaps, by developing and applying new methodologies in order to better estimate the burden of mental disorders. FundaMentalHM will (i) provide the most comprehensive detailed analysis of comorbidity between mental disorders and other general medical conditions, (ii) advance the area of science related to health metrics by incorporating dependent (instead of independent) comorbidity to the estimates, and (iii) use innovative methods to better estimate the excess mortality associated with mental disorders. In accomplishing FundaMentalHM’s objectives, I will provide a more accurate, unbiased view of the true burden – including true number of deaths – associated with mental disorders. These estimates are essential in order to guide the WHO Mental Health Action Plan 2013-2020 and the UN Sustainable Development Goals (SDGs). In addition, I expect that the suite of methods developed as part of FundaMentalHM project can be applied to a wide range of other disorders.