© 2018 by Türkiye Klinikleri.Objective: Hairy cell leukemia (HCL) is a clonal B-cell disorder characterized by infiltration of the bone marrow, peripheral blood, spleen, liver and lymph nodes by malignant B-cell with circumferential cytoplasmic projections. Median survival before purine analogues such as cladribine and pentostatin was only 4 years, but this subsequently increased to 15 years. The aim of this article was to evaluate the clinical characteristics and treatment outcome of patients with HCL. Material and Methods: The clinical characteristics and treatment outcome of patients diagnosed with HCL and treated with cladribine at the Karadeniz Technical University, Faculty of Medicine, Department of Hematology between October 2007 to June 2015 were evaluated retrospectively. Results: Fifteen out of 16 patients were males and 1 females and the median age was 54 (range 35-75) years. Fifteen patients (94%) achieved a complete hematologic response (CHR), 1 (6%) a partial response (PR) with cladribine. Eight patients (50%) relapsed and median progression-free survival was 78 months. When patients' age and comorbid conditions at time of relapse were analyzed, 4 patients received rituximab as a single agent and 2 received cladribine. Five patients (83%) achieved CHR and 1 (17%) PR. Then, 3 patients (50%) observed the second relapse and median progression-free survival was 54.7 months. Median overall survival for all patients was 105 months and 8-year median overall survival rate was 66%. Conclusion: We conclude that cladribine is an effective and safe therapeutic option in HCL. Rituximab can be used in patients not appropriate for cladribine at the time of relapse and the combined use can enhance the effectiveness of treatment.