Background and Purpose A variety of methods may be employed to assess pelvic floor muscle activity, the most widely used being digital vaginal assessment. However, this is a subjective form of assessment and consequently there are issues concerning reliability when two or more clinicians are involved in assessment before and after treatment of patients with urinary incontinence. This article presents the results of a study assessing inter-tester reliability between four clinicians on three different sites. Methods Thirty patients (ten for each clinician from three sites) were assessed by four clinicians. One clinician from each of the three sites was compared to a fourth. Each patient was assessed twice (once by clinician 1, 2 or 3 and once by clinician 4). All four clinicians adhered to the same written protocol and were prevented from conferring until the end of the investigation. Results For clinicians 1 and 3 there were few discrepancies between their scores and those of clinician 4. However, initially there were considerable differences in assessment techniques between clinicians 2 and 4. After appropriate training the disparity between these two clinicians was considerably reduced. Conclusions Inter-tester reliability should not be assumed between clinicians and should be established when two or more clinicians are involved in pre-and post-treatment assessment. If disparity does occur between assessors the difference in assessment technique may be overcome with appropriate training.