Objective: To determine the cost-effectiveness of standard strategy (interferon alpha) versus Cladribine (2-chlorodeoxyadenosine) and Cladribine with interferon alpha treatment for patients with hairy cell leukemia. Methods: A cost-effectiveness analysis was performed. Efficacy of standard treatment strategy, Cladribine and Cladribine with interferon treatment, was estimated from a previous clinical trial held in Moscow HRC RAMS. A total of 160 patients entered the trial. Three group patients with hairy cell leukemia were assigned to receive: 1st group - interferon alpha (3 million units thrice a week), 2nd group - Cladribine (0.1mg/kg daily as a continuous intravenous infusion over seven days), 3rd group received Cladribine with interferon alpha. Direct medical costs (cost of drug administration, resource utilization, duration of hospitalization) were estimated. Achievement of remission was used as effectiveness. Unit costs were based on detailed data from the Moscow Medical Sechenov Academy. The rate of exchange was 24.4 rubles for USD$1 . Results: direct medical costs were RUR93 477 for group 1 (C1), RUR91756 for group 2 (C2) and RUR40 436 for group 3 (C3). Achievement of remission = 70.0 % (E1), 99.0% (E2), 99.0% (E3), for each group respectively. The final calculation of cost / effectiveness ratio (CER) was: CER1=RUR131079 , CER2=RUR94421 and CER3=RUR40845 per one patient for group 1, 2, and 3 respectively. Conclusion: Cladribine with interferon alpha usage versus standard therapy is more cost-effective in the treatment of patients with hairy cell leukemia.