OBJECTIVE: We sought to assess interrater reliability of the International Continence Society (ICS)/International Urogynecological Association (IUGA) classification system of vaginal mesh-related complications and compare this with several other available complication classification systems. STUDY DESIGN: This was a retrospective analysis of mesh-related complications in patients presenting after pelvic organ prolapse or incontinence surgery. The complications were classified by 2 independent reviewers using the ICS/IUGA classification system as well as 3 other available classification systems. Interrater reliability was assessed using percent agreement and the weighted κ statistic. RESULTS: The ICS/IUGA mesh complication classification system was found to have poor interrater reliability (κ = 0.15-0.78). The other systems yielded a κ that ranged from 0.18-0.60, but were too general or could only be applied to 68% of the complications. CONCLUSION: The complexity of the ICS/IUGA mesh complication system, the large number of categories, and lack of clarity likely contribute to its poor interrater reliability.