In order to evaluate the presence of electrophysiologic signs of autonomic dysfunction (AD) in newly diagnosed diabetic children, cardiovascular reflex tests were performed in 55 (30 female, 25 male) newly diagnosed insulin-dependent diabetes mellitus (IDDM) patients aged 10.3–20.7 years (mean ± S.D.: 15.2 ± 5.6). Ten (18.2%) diabetic children had cardiovascular AD, defined as abnormal results in 2 of 5 tests. Autonomic function tests were assessed at entry and after 12, 24, and 36 months of the study. All diabetic children received human insulin and followed an intensive insulin treatment (3 or 4 injections per day), associated with a teaching program of self-management of the disease. In the 3 years of follow-up, all children improved the quality of metabolic control (glycosylated hemoglobin, HbA_1c: 10.3 ± 1.1 % versus 7.7 ± 0.9; P < .01) and manifested no significant difference between baseline and follow-up values of autonomic function tests which remained unchanged in spite of this improvement. Cardiovascular autonomic dysfunction can be present in newly diagnosed IDDM children and it seems to be stable in children who follow an intensive insulin injection therapy.