This dataset contains relative risks, excess mortality, and death count estimates computed from probabilistically linked hospital and mortality records for 72,021,918 patients in the Brazilian Public Health System (SUS) between January 1, 2000, and April 21, 2015. Follow-up duration was measured from the date of the patients’ first hospitalization until their death, or until April 21, 2015. Severe mental illness was defined as schizophrenia, bipolar disorder, or depressive disorder by ICD-10 codes used for the admission. Relative risks were calculated with 95% CIs, comparing mortality among patients with severe mental illness with those with other diagnoses for patients aged 15 years and older. Ill-defined causes of death were redistributed according the Global Burden of Disease study (GBD) methodology when present as the underlying cause.