Objective To investigate the clinical, pathology, diagnosis and treatment of the lower urinary system dysfunction among chronic recreational ketamine abusers. Methods From 2000-2008, 20 ketamine abusers(14 men and 6 women; mean age, 22.3 years), from 3 hospitals in Guangzhou and Hongkong, and suffering from lower urinary tract dysfunction was reported. All of them had abused ketamine for 1 to 4 years, and presented with severe lower urinary tract symptoms. Complaint of severe frequency, urgency, urge incontinence, and painful haematuria was common. Urine cultures were negative. Six men suffered from severe dysuria. B ultrasound examination of 16 cases demonstrated the presence of bilateral hydronephrosis. Fourteen IVU and 10 CT investigations demonstrated the presence of bilateral hydronephrosis, bladder contraction, and 1 case showed papillary necrosis of the kidney. Different levels of abnormal liver function and chronic/acute renal failure were observed. All of the patients were required to withdraw the narcotics and the experimental medicine were given. Results The biopsies of 6 cases demonstrated the cystitis. Twelve cases' symptoms were reversible after these patients stopped or reduced the frequency and amount of ketamine abuse. Pentosan polysulfate sodium and sodium hyaluronate solution relieved the symptoms of 6 patients. Conclusions "Street ketamine" associated urinary system dysfunction might be a kind of in flammatory process involving the upper and lower urinary tract. Underlying aetiology and treatment methods necessitate further study.