Background & Aims Acute liver failure (ALF) caused by hepatitis B virus (HBV) infection can occur after immunosuppressive treatment and be fatal, although it might be preventable. We aimed to characterize the causes, clinical course, and short-term outcomes of HBV-associated ALF after immune-suppressive therapy, compared with patients with HBV-associated ALF without immunosuppression (control subjects). Methods We performed a retrospective multicenter study of 156 consecutive patients diagnosed with HBV-associated ALF (22 with a solid or blood malignancy) enrolled in the Acute Liver Failure Study Group registry from January 1998 through April 2015. We collected data on results of serologic and hepatic biochemistry analyses, grade of hepatic encephalopathy, Model for End-Stage Liver Disease score, and King's College criteria. We also collected data on clinical features, medical therapies, and complications in the first 7 days following study enrollment. Logistic regression was used to identify factors associated with transplant-free survival at 21 days in HBV-associated ALF (the primary outcome). Results Among patients with HBV-associated ALF, 28 cases (18%) occurred after immunosuppressive therapy (15 patients received systemic corticosteroids and 21 received chemotherapy); and 128 cases did not (control subjects, 82%). Significantly greater proportions of patients with HBV-associated ALF after immunosuppression were nonwhite persons, and had anemia or thrombocytopenia than controls (P <.02 for all). The serologic profile of HBV infection, severity of liver failure (based on MELD score), and complications (hepatic encephalopathy or need for mechanical ventilation, vasopressors, or renal replacement therapy) were similar between the groups (P >.17 for all). Factors associated with 21 day transplant-free survival were increased MELD score (odds ratio ∼OR, 0.894 (95% confidence interval 0.842-0.949 per increment), requirement for mechanical ventilation (OR 0.111(0.041-0.300), and immunosuppressive therapy (OR 0.274(0.082-0.923)). Conclusions Within a cohort study of patients with HBV-associated ALF, 18% had received immunosuppressive therapy. Significantly smaller proportions of patients with HBV-associated ALF after immunosuppression survive beyond 21 days than patients with HBV-associated ALF who did not receive immunosuppression. Patients undergoing chemotherapy should be screened for HBV infection and given appropriate antiviral therapies to reduce preventable mortality.