Introduction: Inflammatory Bowel Disease (IBD) is a chronic condition with significant morbidity. Monitoring disease activity is important to determine response to treatment and optimize patient outcomes, however, it is a clinical challenge. The gold standard, endoscopic evaluation, is an invasive test. Non-invasive measures, such as serologic, fecal biomarkers or standardized questionnaires, exist but their utility is still being determined. Red cell distribution width (RDW) measures anisocytosis. An advantage of RDW as a marker for disease activity in IBD is that it is included at no additional cost on a complete blood count. Methods: The aim was to perform a meta-analysis of as a marker for disease activity in IBD. We searched MEDLINE and Web of Science from inception until November 2015 using the search terms: “red cell distribution width” and “inflammatory bowel disease”. The heterogeneity between pooled studies was assessed using the I2 test. Data were pooled under a random effects model and summarized as standardized mean difference (SMD) along with 95% confidence intervals (CI).Figure 1Figure 2Results: The search identified 470 citations, of which 4 studies met our inclusion criteria, and 3 studies had extractable data (438 participants). The reported methodological quality of included studies was low. In patients with Crohn's Disease, patients with active disease had significantly higher levels of RDW compared with patients who had inactive disease (SMD = -3.04, 95% CI -5.27, -0.82, p=0.007). In patients with Ulcerative Colitis, patients with active disease had significantly higher levels of RDW compared with patients who had inactive disease (SMD = -1.40, 95% CI -2.6, -0.19, p=0.02). Conclusion: The findings from this meta-analysis demonstrate that RDW is associated with IBD activity. As an available result on a routinely ordered test (CBC), RDW is a cost-effective and non-invasive means of monitoring IBD activity. More research is needed to evaluate RDW association with objective measures of disease activity including endoscopic and biopsy findings.