The milk-alkali syndrome is the association of hypercalcaemia and renal failure, with or without alkalosis, in the presence of absorption of excessive quantities of calcium, alkali, or both. Two patients with the milk-alkali syndrome are described, one representing an acute, reversible disorder and the other demonstrating a chronic syndrome with only partially reversible renal disease. Differential diagnosis is not difficult and is usually aided by the initial clinical evaluation as well as rapid response to conservative therapy. Because the initial stages of renal insufficiency are often fully reversible, the early identification and treatment of the milk-alkali syndrome can prevent progression to irreversible, chronic renal failure. Although non-absorbable antacids, H2 blockers, and sucralphate are the basis of modern treatment of peptic ulcer disease, the syndrome may still occur, especially in patients who self-treat symptoms of dyspepsia.