BACKGROUND: For diagnosis of hypertension, prompt blood pressure measurement is necessary. In a clinical setting, increased blood pressure is often recorded during urine-holding. The aim of this study was to assess the effect of urine-holding on blood pressure. METHODS: We analyzed 172 subjets who visited a hospital in Pusan for examinafion of pelvic ultrasonography. We measured urine holding time, blood pressure in a urine-holding state, and blood pressure immediately after urination when pelvic ultrasonography was examined. Paired t-test was performed to compare the pre-voiding blood pressure. The relationship between urineholding time and difference in blood pressure were assessed by Pearsons's correlatian coefficients. RESULTS: In subjects who held urine for no less than 3 hours, mean pre-voiding systolic blood pressure was 124.2+/-20.8 mmHg, mean pre-voiding diastolic blood pressure was 78.3+/-13.3 mmHg, post-voiding systolic blood pressure was 120.0+/-21.0 mmHg, and post-voiding diastolic blood pressure was 75.4+/-12.3 mmHg. Mean difference in systolic bload pressure was 4.2+/-10.7mmHg, and mean difference in diastolic blood pressure was 2.8+/-7.7 mmHg(p<0.05). The correlation between urineholding time and differences in systolic and diastolic blood pressure was not significant(P>0.05) CONCLUSION: Urine-holding for no less than 3 hours made systolic and diastolic blood pressure rise. However, the rise in blood pressure was not proportianal to urine-holding time.