We sought to examine the effect of anti-B-cell therapy (rituximab) on cardiac inflammation and function in corticosteroid-refractory cardiac sarcoidosis. Cardiac sarcoidosis (CS) is a rare cause of cardiomyopathy characterized by granulomatous inflammation involving the myocardium. Although typically responsive to corticosteroid treatment, there is a critical need for identifying effective steroid-sparing agents for disease control. Despite increasing evidence on the role of B cells in the pathogenesis of sarcoidosis, there is limited data on the efficacy of anti-B-cell therapy, specifically rituximab, for controlling CS. We reviewed the clinical experience at a tertiary care referral center of all patients with CS who received rituximab after failing to improve with initial immunosuppression therapy, which included corticosteroids. Fluorodeoxyglucose positron emission tomography (FDG PET/CT) images before and after rituximab treatment were evaluated. All images were interpreted by 2 experienced nuclear medicine trained physicians. We identified 7 patients (5 men, 2 women; mean age at diagnosis, 49.0 ± 7.9 years) with active CS who were treated with rituximab. The median length of follow-up was 5.1 years. All individuals, but 1, had received prior steroid-sparing agents in addition to corticosteroids. Rituximab was administered either as 1000 mg intravenously ×1 or ×2 doses, separated by 2 weeks. Repeat dosing, if appropriate, was considered after 6 months. All tolerated the infusions well. Inflammation as assessed by maximum standardized uptake value on cardiac FDG PET/CT uptake significantly decreased in 6 of 7 patients (median 6.0-4.5, Wilcoxon signed rank z -1.8593, W 3), whereas the left ventricular ejection fraction improved or stabilized in 4 patients but decreased in 3. The mean left ventricular ejection fraction was 40.1% and 43.3% before and after treatment, respectively (P = .28). Three patients reported improved physical capacity, and 5 patients showed improved arrhythmic burden on Holter monitoring or implantable cardioverter-defibrillator interrogation. One patient subsequently developed a fungal catheter-associated infection and sepsis requiring discontinuation. Rituximab was well-tolerated and seemed to decrease inflammation, as assessed by cardiac FDG PET/CT in all but 1 patient with active CS. These data suggest that rituximab may be a promising therapeutic option for CS, which deserves merits further study.