Fifty-two patients had secondary operations for recurrent peptic ulcer that occurred after usually acceptable definitive operations. One group of patients with recurrences in the early months and years showed high residual acidity that was frequently attributable to apparently technical faults (28), the most frequent being incomplete vagotomy (19). In two patients, virulent ulcer diathesis, not Zollinger-Ellison syndrome, eventually demanded total gastrectomy. Eight patients, however, apparently had had technically complete initial operations that were inadequate for the degree of ulcer diathesis. Another group of recurrences developed late (after two years), and were frequently associated with low or normal acidity. Eleven patients whose disease was usually associated with recurrent mild bleeding, alcoholism, and equivocal roentgenographic and operative findings remain symptomatic to varying degrees, despite secondary operations of generally approved types.