OBJECTIVE: To validate various noncontrast CT (NCCT) predictors of hematoma expansion in a large international cohort of ICH patients and investigate whether intensive blood pressure (BP) treatment reduces ICH growth and improves outcome in patients with these markers. METHODS: We analyzed patients enrolled in the Antihypertensive Treatment of Acute Cerebral Hemorrhage II (ATACH-II) randomized controlled trial. Participants were assigned to intensive (systolic BP <140 mm Hg) vs standard (systolic BP <180 mm Hg) treatment within 4.5 hours from onset. The following NCCT markers were identified: intrahematoma hypodensities, black hole sign, swirl sign, blend sign, heterogeneous hematoma density, and irregular shape. ICH expansion was defined as hematoma growth >33% and unfavorable outcome was defined as modified Rankin Scale score >3 at 90 days. Logistic regression was used to identify predictors of ICH expansion and explore the association between NCCT signs and clinical benefit from intensive BP treatment. RESULTS: A total of 989 patients were included (mean age 62 years, 61.9% male), of whom 186/869 experienced hematoma expansion (21.4%) and 361/952 (37.9%) had unfavorable outcome. NCCT markers independently predicted ICH expansion (all p < 0.01) with overall accuracy ranging from 61% to 78% and good interrater reliability (k > 0.6 for all markers). There was no evidence of an interaction between NCCT markers and benefit from intensive BP reduction (all p for interaction >0.10). CONCLUSIONS: NCCT signs reliably identify ICH patients at high risk of hematoma growth. However, we found no evidence that patients with these markers specifically benefit from intensive BP reduction. CLINICALTRIALSGOV IDENTIFIER: NCT01176565.