In approximately 50% of cases of Type I diabetes mellitus in children over 8 years old autogenous insulin production is regenerated so well, either spontaneously or by the immunological form of therapy communicated, that the heterogeneous insulin originally administered to preserve life can be reduced and finally discontinued altogether in the course of the first 4 to 6 weeks. The complete remission renders further administration of heterogeneous insulation unnecessary. If this reduction in the quantity of insulin is not attempted, the residual autogenous insulin production will be slowly but surely suppressed by the heterogeneous insulin via its interference with the feedback mechanism. Restoration of the capacity to produce insulin, and thus a possible cure of Type I diabetes mellitus, only appear possible if an attempt is made during the first remission to stimulate regeneration of the beta-cells via nesidioblastosis. Regeneration is aided by the immunotherapy described: firstly, elimination of the obstructed antigen-antibody complexes causing and sustaining the immunological inflammation, and secondly the production of T-suppressor cells to eliminate immunological processes. Basically, in the light of observations of "long-term remissions" reported in the literature, a clinical and biochemical "cure" of Type I diabetes mellitus by immunological means appears possible. The present paper reports on a preliminary series of mainly clinical observations in 13 children with newly diagnosed Type I diabetes mellitus. In approximately 50% of the cases remissions lasting over 2 months were achieved, and some lasted for almost 18 months.