The impact of female sex hormones on the rhythmic urethral pressure variations (UPV) was analysed based on data from one hour urethral pressure recordings from 10 healthy fertile female volunteers measured three times during the menstrual cycle and from 12 healthy postmenopausal women measured twice within two months. The mean maximum urethral pressure (mMUP) and the mean maximum urethral closure pressure (mMUCP) had a median value of 66.5 (Interquartile 58.0-86.0) and 60.0 (49.0-80.0) cm.H2O respectively in the healthy fertile females. The postmenopausal women had a significantly lower mMUP and mMUCP of 55.5 (48.5-58.5) and 43.5 (35.5-47.0) cm.H2O) respectively. Rhythmic UPV was recorded inhealthy fertile and postmenopausal women. Frequency analysis of the UPV revealed a frequency spectrum from 0.0015 to 0.035 Hz on top of which were respiration fluctuations and vascular pulsations. The UPV amplitude was related to the mMUP and increased with increasing mMUP. The parameters analysed were stable during the menstrual cycle and during menopause. Thus no difference in the UPV frequencies or amplitudes was observed between the healthy fertile and the postmenopausal women. The investigation shows that the pressure variation in urethra apparently is not modulated by female sex hormones.