There are few data on platelet function in intracerebral hemorrhage (ICH). We prospectively enrolled 69 patients with ICH and measured platelet function on admission. Aspirin use before ICH was associated with reduced platelet activity. Less platelet activity was associated with intraventricular hemorrhage (516.5 [interquartile range (IQR), 454-629.25] vs 637 [IQR, 493-654] aspirin reaction units; p = 0.04) and death at 14 days (480.5 [IQR, 444.5-632.5] vs 626 [IQR, 494-652] aspirin reaction units; p = 0.04). Objective measures of platelet function on admission are associated with intraventricular hemorrhage and death after ICH.