Summary Stress urinary incontinence is the most prevalent kind of urinary incontinence in women. Treatment efficiency depends on the type of stress urinary incontinence. Purpose of the study: The purpose of the study was to assess the differences of values of leaking indexes in women with different types of stress urinary incontinence. Material and methods: 64 patients were hospitalized at Obstetrics and Gynecology Department of Silesian Medical University between 2005 and 2007. All patients included in the study were diagnosed with stress urinary incontinence (SUI) based on medical history, clinical evaluation, pad test and urodynamic evaluation. The study population was divided into three groups according to VLPP and MUCP. Leaking indexes were calculated as a quotient of the area under the curve of leakage and the area under the curve of bladder pressure during the Valsalva manoeuvre. Results: The values of leaking indexes and relative leaking indexes in different types of SUI were compared. Statistically significant differences between relative leaking indexes for groups of women divided according to MUCP and VLPP criterion were found. Conclusions: Judging from statistically significant differences in relative leaking indexes between groups of women with different types of SUI, relative leaking indexes might be of use in differential diagnosis of types of SUI.