Between 1948 and 1975 147 patients were treated surgically for developmental stenosis of the lumbar vertebral canal, measurement of the mid-sagittal diameters in the whole area of stenosis being performed in 116 patients. Ninety-two of these patients were followed up for periods varying between one and twenty years. About two-thirds were completely relieved fo symptoms and signs. Sciatica and intermittent claudication were more frequently cured than radicular deficit and lumbago, the latter being the most frequent persisting symptom. A permanent neural deficit as a result of the surgical procedure was noted in two cases. A detailed presentation of the technique, complications and results is given.