Cytomegalovirus infection of the gastrointestinal tract is a relatively common occurrence in patients receiving immunosuppressive drugs, those infected with HIV, or those who are transplantant recepients. CMV infection may be diagnosed if typical intranuclear inclusion bodies are seen on standard hematoxylin and eosin (H&E) stain. However, the sensitivity of H&E exam for CMV infection is low. Immunohistochemistry (IHC) exam performed on colon biopsy specimens is more sensitive than routine histologic exam and has excellent specificity. Currently IHC is considered the gold standard for detecting CMV CMV infection in patients with refractory or complicated IBD should be ruled out before aggressive immunosuppressive therapy for treatment-resistant disease to decrease morbidity and mortality.