Background Transarterial chemoembolization (TACE) is the standard treatment for intermediate-stage hepatocellular carcinoma (HCC). It is unknown whether conventional TACE (cTACE) should be continued or abandoned after initial nonresponse for intermediate-stage HCC. The optimal number of sessions before abandoning cTACE remains debated. Purpose To define the number of sessions that patients who do not respond to treatment (hereafter, nonresponders, with stable disease [SD] or progressive disease [PD]) should undergo before abandoning cTACE. Materials and Methods Patients with intermediate-stage HCC and Child-Pugh A liver function who underwent consecutive cTACE sessions between January 2005 and December 2012 were retrospectively included from three centers. Radiologic response rate to each session and its correlation with overall survival were evaluated. Response was assessed by modified Response Evaluation Criteria in Solid Tumors. A nomogram constructed by using tumor size, tumor capsule, and α-fetoprotein to predict patients who responded to treatment (hereafter, responders) was validated with sensitivity and specificity. Results This study evaluated 4154 patients (mean age, 58 years ± 6 [standard deviation]; 3777 men; primary cohort, 3442 patients [mean age, 58 years ± 6; 3129 men]; validation cohort, 712 patients [mean age, 58 years ± 7; 648 men]). Response rate to first cTACE was 35.6% (1227 of 3442, primary cohort) and 36.7% (261 of 712, validation cohort). For patients with SD who were nonresponders to first cTACE, the response rates after second cTACE were 46.1% (719 of 1560) and 48.4% (147 of 304); for patients with SD who were nonresponders to the second cTACE session, the response rates after the third cTACE session were 58.3% (591 of 1014) and 48.5% (98 of 202). For patients with SD who were nonresponders to third, fourth, and fifth cTACE sessions, response rates after fourth, fifth, and sixth cTACE sessions were less than 10%. All response rates in patients with PD who were nonresponders to the next cTACE were less than 5%. Responders to first, second, and third cTACE had higher 5-year overall survival than nonresponders (all P < .001) but responders to the fourth cTACE did not (P = .21). The sensitivity and specificity of a nomogram predicted responders to third cTACE: 75.0% and 79.4% (internal validation) and 78.6% and 87.0% (external validation), respectively. Conclusion Three sessions were recommended before abandoning conventional transarterial embolization (cTACE) for intermediate-stage hepatocellular carcinoma. The nomogram developed in this study identified responders to third cTACE. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Georgiades in this issue.