Abstract: Background: In Obsessive Compulsive Disorder (OCD) current standard pharmacotherapies may be of limited efficacy. Non-conventional interventions such as Complementary and Alternative Medicine (CAM), self-help techniques, and lifestyle interventions are commonly used by sufferers of OCD, however to date no systematic review of this specific area exists.Methods: We conducted a systematic review of studies using CAM, self-help, and lifestyle interventions for treatment of OCD and trichotillomania (TTM). PubMed, PsycINFO, China Academic Journals Full-text Database, The Cochrane Library and CINAHL were searched (up to Jan 11th 2011), for controlled clinical trials using non-conventional interventions for OCD. A quality analysis using a purpose-designed scale and an estimation of effect sizes (Cohen’s d) where data was available, were also calculated.Results: The literature search revealed 14 studies that met inclusion criteria. Methodological quality of nutraceutical studies (nutrients and herbal medicines) were rated as high (mean 8.6/10), whereas mind-body or self-help studies were poorer (mean 6.1/10). In OCD, tentative evidentiary support from methodologically weak studies was found for mindfulness meditation (d=0.63), electroacupuncture (d=1.16), and kundalini yoga (d=1.61). Better designed studies using the nutrient glycine (d=1.10), and traditional herbal medicines milk thistle (insufficient data for calculating d) and borage (d=1.67) also revealed positive results. A rigorous study showed that N-acetylcysteine (d=1.31) was effective in TTM, while self-help technique “movement decoupling” also demonstrated efficacy (d=0.94). Mixed evidence was found for myo-inositol (mean d=0.98). Controlled studies suggest that St John’s wort, EPA, and meridian-tapping are ineffective in treating OCD.Conclusions: While several studies were positive, these were un-replicated and commonly used small samples. This precludes firm confidence in the strength of clinical effect. Preliminary evidence however is encouraging, and more rigorous research of some of the more hypothesis-based interventions in the treatment of OCD and TTM may be indicated.