Given that hypertension is now relatively well controlled and use of antiplatelet agents has increased, our primary aims were to investigate the risk of intracerebral hemorrhage (ICH) associated with hypertension and use of antiplatelet agents. In this city-wide case-control study, 370 consecutive cases of primary ICH, verified by CT or autopsy, were identified from one of 13 Melbourne hospitals. Ten subjects (or their next of kin) could not be located and 29 refused to participate, resulting in 331 eventual cases. Patients were aged between 18 and 80 years and had no prior stroke. Population-based control subjects were individually age- (+/- 5 years), sex-, and geographically matched to subject cases. A questionnaire administered to participants (or next of kin) elicited information about prior exposure to various potential risk factors. Hypertension approximately doubled the risk of ICH (odds ratio, 2.55; 95% confidence interval, 1.72 to 3.79). The use of aspirinlike drugs, in doses used for secondary prevention of ischemic stroke or cardiac disease, was not associated with an increased risk of ICH (odds ratio, 0.66; 95% confidence interval, 0.20 to 2.21). Factors associated with a reduced risk of ICH were a history of cardiovascular disease, arthritis, or high cholesterol level; being moderately overweight or using hormone replacement therapy; and drinking coffee. Hypertension was the most important risk factor for ICH but not as high as previously reported, nor was it higher than that reported for ischemic stroke. There was no evidence for any association between the use of aspirinlike drugs and ICH.