The objective of this study is to define the effect of estrogen replacement therapy (ERT) on cystometric parameters in healthy postmenopausal women. Eighteen postmenopausal women treated with ERT and sixteen women without ERT were included into the study. Both groups were comparable in terms of age, parity, body mass index and menopausal period. ERT group had received daily conjugated estrogen 0.625 mg plus medroxyprogesterone acetate 2.5 mg for four months. The other group were given placebo. At the end of treatment, cystometric and uroflowmetric investigation were performed. We noted maximum capacity, first sensation, vesical pressure during maximum desire to void, maximum flow, and avarage flow. Mann-whitney U test was used for statistical analysis. A p value < 0.05 was set as significant. Maximum cystometric capacity (ml), first sensation (ml), and vesical pressure (cm H2O) were 398,38±21.04, 176.88±17.18, and 36.72±3.04 in ERT group respectively and 289.81±21.04, 99.82±27.70, and 29.20±2.18 in the nontreated group. The difference was statistically significant (p<0.05). There was no significant difference between two groups in terms of maximum flow (ml/sec), and average flow (ml/sec), which were 24.04±1.56, and 12.72±3.70 in the treated group respectively and 22.12±3.20, and 10.27±2.38 in the other group (p> 0.05).ERT has significant effect on cystometric parameters in healthy postmenopausal women and this may positively contribute to the quality of life in elderly.