Abstract：Chronic lymphocytic leukemia in the ureter is rare in primary clinical observations. There were only 2 cases in the reported literature, thereby, it is often ignored, which would make its diagnosis and treatment difficult., An 83-years-old male patient with known chronic lymphatic leukemia accompanied with prolymphocytic increase (CLL/PL) is reported in this paper. Repeated urinary tract infection was the clinical presentation. Ultrasound and urinary system magnetic nuclear Resonance Water Imaging (MRU) indicate the obstruction of low right ureter and dilation of ureter and renal pelvis. After 10 months of dynamic observations, the symptoms such as dysuria, frequent urination, among others,l were aggravated. Then, the patient accepted the chemotherapy of RF (Fludarabine and Rituximab). After the therapy, CLL evaluation of the curative effect shows to be complete remission. Review MRU and ultrasonic sound show that the obstruction was alleviated, and the prostate sizes before and after treatment had no significant change. The patient condition saw no recurrence in 17-month follow-up visit after the therapy. This case reminds us that the possibility of malignant lymphoma of the lymphocytic system should be considered in cases of ureter obstruction when the cause is uncertain. And the condition of original disease involvement should be paid attention if ureteral obstruction appears in patients suffering from diseases of the lymphatic system.