Background: Persons diagnosed with mental disorders are at elevated risk for a range of fatal and non-fatal adverse outcomes. Those discharged from psychiatric inpatient settings have been shown to be at especially high risk. Previous studies have examined adverse outcomes post-discharge predominantly as individual outcomes in separate studies, not allowing comparison of risks due to differences in the study population, outcome measures and design. To date, no study has comprehensively investigated multiple adverse outcomes in a single large national cohort. Methods: I utilised Danish national registry data including every person born in Denmark between 1967 and 2000. Participants were followed up from their 15th birthday until emigration or Denmark or date of outcome of interest, whichever came first. I used open cohort and matched cohort designs and survival analysis techniques to calculate risk estimates versus the general population without psychiatric admission for an array of fatal and non-fatal adverse outcomes including violence and homicide perpetration and victimisation. Results: Persons discharged from psychiatric inpatient services had markedly higher absolute and relative risks for all outcomes examined compared to those without a history of psychiatric admission. The relative risk was higher for unnatural than for natural deaths and higher for homicide perpetration than victimisation. Those diagnosed with psychoactive substance misuse were at higher risk than other psychiatric diagnostic categories. The relative risk was highest in the time directly following discharge and declined over time but remaining elevated throughout. Conclusion: Enhanced liaison between inpatient services and community care is needed to the risk of post-discharge adverse outcomes. Given the markedly elevated risk among persons diagnosed with substance misuse disorders, interventions targeting these disorders should be offered at an early stage of the inpatient treatment episode.