© 2021 Elsevier Inc.Introduction/Background: The emergence of novel agents targeting the B-cell receptor pathway and BCL-2 has significantly changed the therapeutic landscape of CLL. We evaluated the safety and efficacy of single-agent ibrutinib in relapsed/refractory CLL in real-world settings. Patients/Methods: A total of 200 relapsed/refractory CLL patients with a median age of 68 were included in this retrospective, multicenter, non-interventional study. Data of the study were captured from the patient charts of the participating centers. Results: The median for lines of previous chemotherapy was 2 (1-6); 62 (31.8%) patients had del17p and/or p53 mutations (del17p+/p53mut). Of the study group, 146 (75%) patients achieved at least PR, while 16 (8.7%) patients discontinued ibrutinib due to TEA. The most common drug-related adverse events were neutropenia (n: 31; 17.4%) and thrombocytopenia (n: 40; 22.3%), which were ≥ grade 3 in 9 (5%) and 5 (3.9%) patients, respectively. Pneumonia (n: 42; 23.7%) was the most common nonhematologic TEA. Atrial fibrillation (n: 5; 2.8%) and bleeding (n: 11; 6.3%) were relatively rare during the study period. Within a median follow-up period of 17 (1-74) months, 42 (21%) patients died. The estimated median OS of the study cohort was 52 months. Only the response to ibrutinib (CR/PR vs. SD/PD) was significantly associated with OS. Conclusion: Our results indicate good safety and efficacy for single-agent ibrutinib in R/R CLL in daily practice.