In 42 gastrectomized patients with low serum B12 the vibration perception threshold (VPT) was significantly elevated as compared with a control group. Forty patients were followed up after 6-12 months of intensive vitamin B12 therapy. Within an adequately treated group (25 patients) remission of symptoms and signs of peripheral neuropathy was observed, including a statistically significant reduction of the VPT measured on the medial malleolus and big toe. Such a reduction was not observed in the adequately treated group of patients with myclopathy. Findings in the inadequately treated group were less definite, both as regards remission of clinical findings and VPT. In four untreated patients the neurological symptoms and signs progressed during the follow-up period. On the basis of these findings intensive and long-lasting treatment with vitamin B12 is recommended for gastrectomized patients showing signs of neuropathy.