Abstract Background Fathers’ parental leave has been associated with decreased risks of alcohol-related morbidity and mortality. Whether this is attributable to parental leave's health protections (via stress reduction or behavioral changes) or selection effects (via better pre-existing health) remains unclear. Based on the quasi-experimental variation of a Swedish reform that incentivized fathers’ leave use, this study aims to assess whether fathers’ parental leave influences their alcohol-related morbidity and mortality. Methods Using total population registers, we identified fathers of children born in Sweden from 1992 to 1997 (n = 220,412). Exposure was indicated by fathers’ reform eligibility (i.e., childbirth after January 1995) and parental leave uptake. Outcomes included rates of alcohol-related hospitalizations with acute (intoxication, mental and behavioral disorders) and chronic alcohol-related diagnoses (other diseases), as well as alcohol-related mortality, up to two, eight and eighteen years after childbirth. Interrupted time series and instrumental variable analyses were used to measure the association of fathers’ reform eligibility and leave uptake, respectively, with alcohol-related health. Results In interrupted time series analyses, exposure to the reform was associated with decreases in fathers’ overall and acute alcohol-related hospitalization rates up to two, eight and eighteen years after birth (e.g., two-year rates: Incidence Rate Ratio [IRR] 0.66, 95% CI 0.51-0.87), with no changes in related mortality. Instrumental variable analyses suggested that alcohol-related hospitalization decreases were driven by fathers’ leave uptake (e.g., two-year rates: IRR 0.16, 95% CI 0.03-0.84). Conclusions Findings suggest that fathers’ parental leave eligibility and uptake may protect against their alcohol-related morbidity in the short and long term. Parental leave incentives could be an effective public health instrument to reduce alcohol-related harms in society. Key messages • Parental leave could be protective for fathers’ alcohol-related health by reducing stress and discouraging risk behaviors, although selection into leave use may confound this association. • Utilizing the quasi-experimental variation of a Swedish fathers’ parental leave policy, this study highlights the beneficial effects of leave use for fathers’ alcohol-related outcomes.