Hypertension as a risk factor for intracerebral hemorrhage (ICH) is poorly quantified, particularly in the setting of the use of modern antihypertensive agents. To investigate this, we studied 331 consecutive hospital cases of primary ICH verified by computed tomography or autopsy, occurring during the period 1990 through 1992, and 331 age- and sex-matched community-based control subjects in a city-wide study involving 13 hospitals. Hypertension approximately doubled the risk of ICH (adjusted odds ratio [OR], 2.45; 95% confidence interval [CI], 1.61 to 3.73). The OR associated with hypertension was significantly greater among those who had ceased taking medications, supervised and unsupervised (OR, 4.98; 95% CI, 2.25 to 11.02), compared with those who had not (OR, 1.95; 95% CI, 1.20 to 3.16), were under the age of 55 years (OR, 7.68; 95% CI, 2.65 to 22.5), or were current smokers (OR, 6.12; 95% CI, 2.29 to 16.35). The presence of hypertension did not influence size or location of the hemorrhage. However, those dying from ICH displayed a greater risk of ICH due to hypertension than survivors, with the ratio of the two ORs being 5.47 (95% CI, 1.23 to 24.44). These findings provide evidence for a greater increase in risk of ICH due to hypertension among younger persons, current smokers, and those discontinuing antihypertensive therapy. This is the first direct evidence for a link between stopping antihypertensive medication use and stroke risk; targeting these individuals for more intensive monitoring and education on the importance of risk factor modification may help to reduce the impact of this form of stroke. (Hypertension. 1998;31:1223-1229.)