Because of high relapse rates with rituximab combinations, there is an unmet need for new therapeutic agents for treatment of indolent B-cell non-Hodgkin lymphoma (iNHL) or follicular lymphoma (FL). In previous trials, ofatumumab in combination with chemotherapy showed good results in relapsed/refractory FL pretreated with rituximab. This phase 3 trial evaluated the efficacy and safety of single-agent ofatumumab vs single-agent rituximab in rituximab-sensitive relapsed FL that relapsed at least 6 months after completing the last prior treatment with single-agent rituximab or a rituximab-containing regimen. Patients were randomized 1:1 to receive either ofatumumab (1000 mg) or rituximab (375 mg/m2) every week for 4 weeks for the induction phase, followed by once every 2 months for 4 additional doses. The primary endpoint, progression-free survival (PFS) and secondary endpoints, overall response rate (ORR) and overall survival (OS), were evaluated. Overall, 438 patients were assigned to receive ofatumumab (n = 219) and rituximab (n = 219). Baseline characteristics were similar in both arms. The independent review committee assessed whether median PFS was shorter in the ofatumumab arm than in the rituximab arm (16.33 vs 21.29 months), with no significant difference (hazard ratio, 1.15; 95% confidence interval, 0.89-1.49; P = .29) and also showed a lower ORR (50%) compared with the rituximab arm (66%). At the time of analysis, data were not matured for OS results. The number of grade >3 adverse events was higher in the ofatumumab arm (37%) than the rituximab arm (28%). Ofatumumab showed no superiority over rituximab in patients with FL who had relapsed after a rituximab-containing therapy. This study was registered at www.clinicaltrials.gov as #NCT01200589.© 2020 by The American Society of Hematology.