OBJECTIVE: Systemic lupus erythematosus is a multisystem disease with a wide spectrum of clinical and laboratory features. Involvement of the urinary bladder is rarely mentioned in the literature. We conducted this study to examine lower urinary tract function in fe-male patients with SLE. METHODS: We conducted a prospective study on 145 consecutive female SLE patients receiving regular treatments in the Rheumatology Department from October 1999 through June 2000. Each patient was interviewed with a questionnaire comprised of the International Prostate Symptom Score and their clinical histories of SLE. Symptom scores were further correlated with disease severity, which was determined by the SLE disease activity index (SLEDAI) based on clinical and laboratory features. In addition, symptom scores obtained from 177 age-matched healthy females were used as a control. RESULT: Total symptom score(6.24±0.56 vs. 4.26±0.36), irritative symptom score(3.71±0.32 vs. 2.88±0.22), and obstructive symptom score(2.53±0.33 vs. 1.38±0.19) were all significantly higher in the SLE group when compared to the control group. The symptom score showed a significant correlation with disease activity(r=0.30, p＜0.001), but not with disease duration (p＞0.05). Overall, 45(31.0%)patients reported an IPSS of＞7. Those who linked their urinary symptoms to SLE (n=29) had significantly higher symptom scores than those who did not (n=16). Thirty-eight (26.2%)patients reported being ”mostly dissatisfied” with their urination. CONCLUSIONS: Our study suggests that a substantial number of women with SLE present with various degrees of voiding dysfunction that is significantly associated with disease activity. Whether voiding dysfunction is a clinical manifestation of lupus cystitis or secondary to other factors remains to be elucidated.