Cytomegalovirus (CMV) colitis is usually associated with immunosuppressed patients, which by the classic definition are individuals who have immunosuppressed associated conditions (human immunodeficiency virus [HIV], oncology diseases, inflammatory bowel disease, transplant patients) or who are submitted to immunosuppressing therapies (for instance, corticosteroids, chemotherapeutic agents or immunomodulation therapies). In immunocompetent patients, this diagnosis tends to be often missed, leading to a delay in initiating proper management. We present a case of a 91-year-old woman that was diagnosed with CMV colitis without any identified formal immunocompromising factors. We intend to highlight the need to review the definition of an immunosuppressed individual and emphasize that CMV colitis should be considered in the differential diagnosis, especially in elderly patients and those with underlying conditions that can possibly affect their immune status, since prompt diagnosis and treatment are essential and influence the prognosis.