A diagnostic evaluation for cytomegalovirus (CMV) infection is required in patients with inflammatory bowel disease (IBD) who do not respond to steroid or immunomodulatory treatment. However, there is no consensus on an accurate diagnostic method for CMV infection in patients with IBD, and it is difficult to clearly distinguish the exacerbation of ulcerative colitis from CMV colitis. According to several recent studies, the most accurate test method for CMV colitis is quantitative tissue DNA-quantitative PCR, which is recommended as the first-line diagnostic technique along with an immunohistochemistry stain. The benefit of antiviral therapy for CMV infection in patients with IBD is also controversial. Although the definition of viral load is unclear, antiviral therapy can lower the rate of colectomy in CMV infections with a high viral load in patients with IBD. This review presents the latest findings about CMV infections in IBD, based on recently reported studies.