Few treatment options exist for chronic migraine headaches, with peripheral nerve blocks having long been used to reduce the frequency and severity of migraines. Although the therapeutic effects have been observed in clinical practice, the efficacy has never been fully studied. In the past decade, however, several randomized controlled clinical trials have been conducted to assess the efficacy of greater occipital nerve block in the treatment of chronic migraine headaches. A systematic review of the literature was performed in the citation databases PubMed, Embase, MEDLINE, and the Cochrane Library. The initial search of databases yielded 259 citations, of which 33 were selected as candidates for full-text review. Of these, nine studies were selected for inclusion in this meta-analysis. Studies were analyzed that reported mean number of headache days per month in both intervention and control groups. A total of 417 patients were studied, with a pooled mean difference of -3.6 headache days (95 percent CI, -1.39 to -5.81 days). This demonstrates that greater occipital nerve block intervention significantly reduced the frequency of migraine headaches compared with controls (p < 0.00001). Pooled mean difference in pain scores of -2.2 (95 percent CI, -1.56 to -2.84) also demonstrated a significant decrease in headache severity compared with controls (p < 0.0121). Greater occipital nerve blocking should be recommended for use in migraine patients, particularly those that may require future surgical intervention. The block may act as an important stepping stone for patients experiencing migraine headache because of its usefulness for potentially assessing surgical candidates for nerve decompression. Therapeutic, II.