Clinical and urodynamic variables of 49 non-estrogen-supplemented and 23 estrogen-supplemented postmenopausal women with urinary incontinence were compared. We ascertained their estrogenic status via plasma estradiol and estrone levels, as well as from parabasal and superficial cell counts from both the urethra and vagina. The effect of estrogen supplementation, in conjunction with the effect of age and urodynamic diagnosis, was studied in relation to filling-phase urodynamic data and incontinence severity and outcome variables. Analysis of covariance was used. No direct effect of estrogen supplementation was noted on parameters of urethral function. In patients with detrusor instability, a borderline direct positive effect (P = .06) was noted in the volume needed to reach maximal cystometric capacity from the first sensation to void. For these patients, the magnitude of fluid loss was greater without estrogen supplementation. However, this difference did not reach statistical significance. Nocturia was significantly less frequent in the estrogen-supplemented groups (P = .04). Estrogen-supplemented patients had a higher incidence of positive bulbocavernosus reflex (P = .01). These observations suggest that hypoestrogenism may affect the sensory threshold of the lower urinary tract of incontinent postmenopausal women.