BACKGROUND Primary intraventricular hemorrhage (PIVH) is an uncommon type of intracerebral hemorrhage. Owing to its rarity, the clinical and radiological factors affecting outcomes in patients with PIVH have not been widely studied. MATERIAL AND METHODS We retrospectively reviewed 112 patients (mean age 53 years) treated for PIVH at our institution from January 2004 to December 2014. Clinical and radiological parameters were analyzed 3 months after initial presentation to identify factors associated with clinical outcomes, as assessed by the Glasgow Outcome Scale (favorable ≥4, unfavorable <4). RESULTS Of the 99 patients who underwent angiography, causative vascular abnormalities were found in 46%, and included Moyamoya disease, arteriovenous malformation, and cerebral aneurysm. At 3 months after initial presentation, 64% and 36% of patients were in the favorable and unfavorable outcome groups, respectively. The mortality rate was 19%. However, most survivors had no or mild deficits. Age, initial Glasgow Coma Scale (GCS) score, simplified acute physiology score (SAPS II), modified Graeb score, and various radiological parameters reflecting ventricular dilatation were significantly different between the groups. Specifically, a GCS score of less than 13 (p=0.015), a SAPS II score of less than 33 (p=0.039), and a dilated fourth ventricle (p=0.043) were demonstrated to be independent predictors of an unfavorable clinical outcome. CONCLUSIONS In this study we reveal independent predictors of poor outcome in primary intraventricular hemorrhage patients, and show that nearly half of the patients in our study had predisposing vascular abnormalities. Routine angiography is recommended in the evaluation of PIVH to identify potentially treatable etiologies, which may enhance long-term prognosis.