12 recent acute-onset ketotic juvenile diabetics were optimally treated during 5 +/- days by means of an external artificial pancreas. Remission of diabetes occurred in 9 patients (75%). In a comparative group of 28 patients treated by conventional subcutaneous insulin, only 3 (11%) steady remissions were obtained. In a third group of 6 patients treated by insulin infusion without feed-back control, only 1 remission (17%) was obtained. The difference between these two groups and the first group (patients treated by the artificial pancreas) is significant (p less than 0.01). Urinary C-peptide/blood glucose ratio showed a steady improvement of insulin secretion during the remission period. At this time, actuarial analysis shows that the number of patients still in remission decreases during the first 10 months but seems to stabilize after this period. Duration of our remissions is equal to the duration of the "spontaneous" remissions taken from the literature. New treatment able to sustain the residual insulinsecretion during the remission phase (with presently can be induced frequently with our technique) are still to be found.