Primary cytomegalovirus infection and gastric ulcers in normal host. A 42-year-old woman presented with epigastric pain and vomiting. Upper gastrointestinal endoscopy revealed three gastric ulcers. Histologic examination of biopsies from the ulcers showed cytomegalovirus inclusion bodies. The appearance of IgM antibodies to cytomegalovirus indicated a recent and primary infection. Stored serum from her last pregnancy 17 months previously contained no cytomegalovirus antibodies. A thorough evaluation of her immune system revealed no abnormality. We are aware of only two other cases where seroconversion was documented in normal hosts. Cytomegalovirus infections in the gastrointestinal tract of normal hosts are very unusual but a common cause of morbidity in immunocompromised hosts. We believe that cytomegalovirus may have a role in the pathogenesis of gastrointestinal lesions in nonimmunocompromised patients. 