AIMS: Pelvic floor muscle training (PFMT) has Level A evidence to treat female urinary incontinence (UI). Recently, indirect training of the pelvic floor muscles (PFM) via the transversus abdominis muscle (TrA) has been suggested as a new method to treat UI. The aim of this article is to discuss whether there is evidence for a synergistic co-contraction between TrA and PFM in women with UI, whether TrA contraction is as effective, or more effective than PFMT in treating UI and whether there is evidence to recommend TrA training as an intervention strategy. METHODS: A computerized search on PubMed, and hand searching in proceedings from the meetings of the World Confederation of Physical Therapy (1993-2007), International Continence Society and International Urogynecology Association (1990-2007) were performed. RESULTS: While a co-contraction of the TrA normally occurs with PFM contraction, there is evidence that a co-contraction of the PFM with TrA contraction can be lost or altered in women with UI. No randomized controlled trials (RCTs) were found comparing TrA training with untreated controls or sham. Two RCTs have shown no additional effect of adding TrA training to PFMT in the treatment of UI. CONCLUSIONS: To date there is insufficient evidence for the use of TrA training instead of or in addition to PFMT for women with UI. Neurourol. Urodyn. 28:368-373, 2009. (c) 2009 Wiley-Liss, Inc.