Purpose: The aim of this study is to determine the efficacy and safety of 2-chlorodeoxyadenosine (Cladribine) in the treatment of patients with hairy cell leukemia.Patients & Methods: Twenty-seven patients with hairy cell leukemia received a single dose of cladribine at a dose of 0.09 mg / kg /day for seven days by continuous I.V. route.Results:Evaluation at one year revealed CR in 92.6% , and treatment revealed mortality of 7.4% .Cladribine therapy was tolerable with mild to moderate toxicity ,mainly in the form of neutropenic fever , GIT toxicity and HZV skin infection .ConclusionCladribine was found to be a well tolerated therapy with acceptable side effects .The disease free and over all survival was as high as 92.6% .However more cases and longer follow up are needed to reach a firm conclusions.