The authors examined the association of gestational hypertensive disorders (hypertension, preeclampsia, eclampsia) with adult cognitive function among men born in 1978-1983 in a well-defined geographic area of northern Denmark. Data from the Danish Medical Birth Registry, the Danish National Registry of Patients, and draft board records were linked. Cognitive function was measured at conscription by using the Boerge Prien group intelligence test. Test scores were converted to the conventional IQ scale (mean = 100 (standard deviation, 15)). Low cognitive function was defined as IQ < 85. Of the 17,457 men who underwent intelligence testing, 891 (5.1%) were born after a pregnancy involving hospitalization for a gestational hypertensive disorder. Compared with conscripts born after normotensive pregnancy, conscripts exposed to maternal gestational hypertension had an adjusted prevalence ratio for low cognitive function of 1.34 (95% confidence interval (CI): 1.01, 1.77). For those exposed to mild preeclampsia and severe preeclampsia/eclampsia, adjusted prevalence ratios were 1.34 (95% CI: 1.09, 1.65) and 1.10 (95% CI: 0.48, 2.51), respectively. The corresponding adjusted mean differences in IQ scores were -2.0 (95% CI: -4.0, 0.0), -3.2 (95% CI: -4.7, -1.8), and -2.0 (95% CI: -7.2, 3.2). In this study, prenatal exposure to gestational hypertensive disorders was associated with slightly reduced adult cognitive performance among male conscripts.