OBJECTIVE Hemangiopericytoma (HPC) is a rare mesenchymal tumor that tends to affect the central nervous system and is associated with distant metastasis and a high recurrence rate. The purpose of this study was to analyze the prognostic factors in patients with primary HPC who received surgical treatment. METHODS This retrospective study reviewed all adult patients with primary HPC of the central nervous system treated from 2001 to 2009 at our institution. Clinical information, adjuvant radiation, and expression levels of Ki-67 and p53 were correlated with patient outcomes. RESULTS The final analysis included 103 patients. The mean follow-up period was 75.9 months ± 36.5 (range, 1-165 months). There was a significant difference in progression-free survival (PFS) (P < 0.001) and overall survival (P = 0.014) between patients who underwent gross total resection versus subtotal resection. Expression of p53 was found in 48.5% of patients and showed utility as an independent unfavorable prognostic factor for PFS (P = 0.006). Multivariate analysis revealed that only extent of tumor resection (P = 0.004) and p53 expression (P = 0.024) were independent prognostic factors for PFS. Adjuvant radiation was found to extend PFS only in the p53-negative expression group (P = 0.044). CONCLUSIONS Gross total resection significantly improves the outcome of patients with primary HPCs, whereas adjuvant radiation contributes significantly to PFS only in patients with negative p53 expression and in patients with incomplete resections. Extent of resection and p53 expression may serve as prognostic markers for the outcome of patients with primary HPC.