Background: There is a concern about worsening of anemia after atrial fibrillation (AF) ablation in anemic patients. We aimed to clarify whether or not patients with anemia who are on an oral anticoagulant therapy are more likely to lose blood after AF ablation. Methods: We studied AF patients in 3 cardiovascular centers who skipped a single dose of direct oral anticoagulants prior to the ablation, and compared the drop in the hemoglobin level 24 hours after the procedure and bleeding complications between the patients with and without preexisting anemia. Results: We identified 183 (15.7%) patients with anemia at baseline out of 1163 patients. The reduction in the hemoglobin level (-0.39±0.71 vs. -0.93±0.9 g/dL; P<0.001) was smaller in the anemic than non-anemic patients. A fall in the hemoglobin level of ≥2 g/dL was less common in anemic patients (1.6% vs. 11.3%; P<0.001). A female gender (odds ratio [OR] 1.62, confidence interval [CI] 1.07-2.45; P=0.02), persistent or longstanding persistent versus paroxysmal AF (OR 1.67, CI 1.13-2.49; P=0.01), ORBIT score ≥3 (OR 3.5, CI 1.34-8.94; P=0.01), and preexisting anemia (OR 0.02, CI 0.004-0.14; P<0.001) were independently associated with the fall in the hemoglobin level of ≥2 g/dL. No difference was noted in the rate of major bleeding complications (1.6% vs. 1.2%; P=0.72). Conclusions: Paradoxically, patients with preexisting anemia may be less likely to lose blood following AF ablation.