Little is known about the natural history of peptic ulcer disease. Its active phase tends to last about 15 years with a high frequency of complications (in 20-25% of cases) and recurrences after initial healing, although subsequently these problems are reduced. Until the advent of the H2 blockers, therapy (whether medical or surgical) failed to alter the course of the disease. Peptic ulcer disease, however, appears to respond positively to therapy with H2 blockers, inasmuch as these drugs at relatively low doses induce rapid healing of the ulcer in a high percentage of patients, while subsequent maintenance treatment at lower doses helps prevent recurrences and complications throughout the entire administration period. In so doing, H2 blockers improve the patients' quality of life.