Foscarnet, administered via a central line, was used for the treatment of 18 episodes of cytomegalovirus (CMV) esophageal ulceration in 15 patients, and in the treatment of 27 episodes of CMV colitis in 22 patients. In 15 of the 18 episodes of the esophageal disease, there was complete loss of symptoms within 2 wk. Only three of the 15 patients responding to foscarnet therapy had a relapse of their esophageal disease. Two of these patients were successfully retreated with foscarnet. Of the 22 patients receiving foscarnet for CMV colitis, four died during foscarnet therapy. Of the 18 patients completing the course of treatment with foscarnet for first-episode CMV colitis, 11 remitted completely and six had a partial remission. All patients with partial remission had a second pathogen responsible for the continuation of their diarrhea. Only one patient completing a course of foscarnet failed to respond microscopically to treatment. Three patients experienced relapse of their CMV colitis, two of whom responded to further courses of foscarnet. Foscarnet is an effective therapy for CMV disease of the gastrointestinal tract, with rapid resolution of clinical symptoms, long-term remission of esophageal disease, and shorter disease-free periods for CMV colitis.