Cytomegalovirus infection of the gastrointestinal tract is a rare serious complication in patients with collagen diseases receiving immunosuppressive agents. We report 3 such cases diagnosed by endoscopy followed by proper treatment. The patients include 38 and 53 years old females with systemic lupus erythematosus. They presented epigastric pain after pulse steroid therapy and combination therapy with steroids and cyclophosphamide, respectively. Their endoscopical findings were multiple small gastric erosions. The other patient was a 60-year-old female with polymyositis who developed rectal bleeding after steroid and imuran therapy. Her endoscopical finding was a discrete, irregular rectal ulcer. The diagnosis of all the patients was confirmed by biopsies of those lesions showing giant cell inclusion bodies and positive staining with anti- cytomegalovirus -antibodies. All patients were treated properly with ganciclovir. We should always keep in mind of a cytomegalovirus infection of the gastrointestinal tract in a patient with collagen disease receiving immunosuppressive agents.