An estimated one third of United States adults use herbal supplements, often without reporting use to their physicians. These supplements can potentially alter bleeding and coagulation during surgery, and when used concomitantly with anticoagulants. Our objective is to provide a comprehensive review of the evidence of bleeding risks of the most popular herbal and dietary supplements. A PubMed search and review of the literature was performed. We found that garlic and hawthorn supplementation are strongly associated with surgical bleeding independent of anticoagulants; cordyceps sinensis, echinacea, and aloe vera are loosely associated with surgical bleeding independent of anticoagulants. In patients on anticoagulants, ginkgo biloba, chondroitin-glucosamine, melatonin, turmeric, bilberry, chamomile, fenugreek, milk thistle, and peppermint are associated with bleeding risk; no evidence was found for bleeding with these supplements independent of anticoagulants. Fish oil, ginseng, and saw palmetto are not associated with bleeding. Evidence for overall bleeding risk associated with St. John’s Wort, ginger, ginkgo biloba, or cranberry supplementation is conflicting. In conclusion, physicians must be aware of the potential anticoagulant effects of these supplements. It is imperative to report dietary and herbal supplement usage to physicians and is best to discontinue non-essential supplement use 2 weeks prior to surgery.