In a randomized double-blind manner, 43 women with grade I and II stress urinary incontinence were treated with either phenylpropanolamine p.o. 50 mg twice daily (Rinexin, 1 tablet b.i.d.) or placebo during two weeks. Urethral CO2 profilometry, with recording of maximum urethral closure pressure (MUCP) and functional urethral length (FUL), and subjective response were considered for effect evaluation. The subjective response of Rinexin was highly significant (p = 0.01) above that of placebo. Clinical improvement was reported by 15 of 21 women on Rinexin and by 8 of 22 women on placebo. A significant increase in MUCP, 14%, was registered in women on Rinexin treatment. This increase was more pronounced in the grade I than in the grade II incontinent women. No statistically significant correlations were obtained between subjective response and increase in MUCP. An increase in FUL was recorded in both two treatment groups, but no statistically significant difference between them was obtained. Adverse drug reactions were rare. No changes in blood pressure occurred. Based on the present study, Rinexin (1 tablet b.i.d.) is an effective and safe medication for female grade I and II stress incontinence and is also recommended as adjunctive therapy to physiotherapy before Teflon injection or operation.