The aim of this study was to identify the value of pelvic floor muscle strength in the diagnosis of female urinary incontinence. One hundred and one women were studied and divided into two groups, Group 1 (n=51) with urinary loss and Group 2 (n=50) without urinary loss. The following aspects were studied: objective, visual, and functional evaluation of the pelvic floor muscles. Objective and functional evaluation of the muscular strength of women who presented urinary loss revealed some significant deficits in muscle strength and pelvic floor perception when compared to the group of women without urinary loss. When we compared pelvic floor muscular strength with a perineometer we noted that continent patients presented higher strength, 38.4cm H2O mean peak contraction, compared to the incontinent group, 26.1cm H20. The mean of the mean supported contraction was 28.1cm H2O for continent and 15.4cm H2O for the incontinent group. The mean duration of contraction was 11.8 seconds for continent and 8.9 for the incontinent group. Pelvic floor muscle strength was insufficient in the incontinent group.