PURPOSE: To present the findings of a risk-stratification survival analysis with use of data collected on a heterogeneous group of patients with hepatocellular carcinoma (HCC) treated with TheraSphere. MATERIALS AND METHODS: Baseline, treatment, and follow-up data were collected and analyzed from 121 TheraSphere-treated patients. Survival analyses were performed to identify those variables most strongly associated with 3-month mortality. The presence of any of the identified risk variables resulted in the assignment of a patient to the high-risk category. RESULTS: Five liver reserve and two non-liver reserve variables were identified and used to stratify patients into low- or high-risk groups. Sixteen of the 33 patients assigned to the high-risk group (49%) did not survive the first 3 months after treatment, compared with six of the 88 patients assigned to the low-risk group (7%; Fisher exact test, P < .0001). Median survival for the low- and high-risk groups were 466 days and 108 days, respectively (hazard ratio, 6.0; P < .0001). Eleven of 12 patients who experienced a treatment-related major complication ending in death were included in the high-risk group. No single variable explained the major complication relationship to treatment. CONCLUSION: Patients with HCC who are being considered for treatment with TheraSpheres should be evaluated for the presence of the risk variables described herein. The absence of these variables is predictive of improved survival (median of 466 days) compared with patients at high risk (median of 108 days).