Hyperprolactinemia has been suspected to increase mortality risk, but the available data are conflicting. The objective of this study was to estimate the association between hyperprolactinemia and all-cause and cardiovascular mortality among patients referred for assessment of prolactin. For this study, adults with no prio pituitary disease who underwent prolactin assessment at 3 university Hospitals in Denmark between 2001 and 2011 were included in a retrospective cohort study. A total of 3 633 patients with a median follow-up time of 5.3 years (IQR 2.7-5.7) were included. Mean (SD) age 39.7 (15.5) years and 78% female. 373/3 633 (10.3%) had hyperprolactinemia and during follow-up 330/3 633 (9.1%) patients died of any cause, and 113/3 633 (3.1%) patients died of cardiovascular causes. In males, hyperprolactinemia was associated with age-adjusted incidence rate ratio (IRR) of 1.86 for all-cause mortality (95% CI 1.22-2.82) and 2.55 (95% CI 1.43-4.55) for cardiovascular mortality. The IRR for all-cause mortality was reduced to 1.37 (0.90-2.08) when adjusted for the use of antipsychotic medication. The association between hyperprolactinemia and cardiovascular mortality remained after adjusting for confounders, for example, chronic renal failure, diabetes, and antipsychotic medication. In females, hyperprolactinemia was not associated with all-cause mortality (IRR 1.45; CI 0.86-2.47) or cardiovascular mortality (IRR 0.58; CI 0.14-2.39). In conclusion, hyperprolactinemia was associated with increased cardiovascular mortality in male patients. This association was not found in female patients. Focus on increased cardiovascular risk in males with hyperprolactinemia is warranted.