Abstract: Objective: To evaluate the therapeutic effect and adverse reaction of oral fludarabine in the treatment of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Methods:Fifteen patients included10CLL patients and 5 SLL patients, and their media age was63years. According to Rai staging,5 CLL patients were in stage Ⅱ,2 in stage Ⅲand 3 in stage Ⅳ. According to the clinical staging, there were 4 SLL patients in stage Ⅲand 1 in stage Ⅲ. Eleven patients were previously untreated while 5 were treated. All the patients received oral fludarabine 40mg/(m2·d) for five consecutive days, repeated every4 weeks for4 cycles at least. Twelve patients went through4 courses of treatment, and the other 3 patients continuously received one or two courses of consolidation therapy. Results: The average course of the 15patients was 4.3. The rate of complete response (CR), partial response (PR) and overall response (OR) were 66.7% (10/15), 26.6% (4/15) and 93.3% (14/15) respectively, and one had no response to treatment. Nine of eleven previously untreated patients achieved CR while PR was obtained in one. And one died because of disease progression. Among four previously treated patients, one achieved CR and three achieved PR. The main adverse reactions were myelosuppression and infection. GradeⅠ～Ⅲneutropenia were found in 5 (33.3%) patients in which1 was with grade Ⅰ, 3 with gradeⅡand 1 with grade Ⅲ. Infection occurred in 3 (20% ) patients. Nonhematologic toxicity was mild. All the adverse reactions were reversible. Conclusion:The oral fludarabine is an effective, safe regimen in patients with CLL/SLL. It is also effective to the previously treated patients. The adverse reactions are mild. The oral fludarabine is a recommendable therapy for the patients with CLL/SLL.