230 highly selective vagotomies (H.S.V.) for chronic duodenal ulcer are carefully studied. Per and postoperative complications are reviewed and compared with the most important reported statistics. A 10-year follow-up gives an indication of the late functional results and evaluation of the percentage of recurrences which lies at around 6%, on first estimation. A complete study of pre- and postoperative gastric secretion tests in duodenal ulcers which did not respond to treatment with Cimetidine and also in patients with very severe hyperacidity is reported, showing that, even in these cases, H.S.V. notably decreases acidity levels and gives satisfactory results. H.S.V. has practically no mortality, a very low morbidity and is followed by excellent functional results. The only factor which remains is the relatively high rate of recurrence which increases with time.