Background: Diabetic ketoacidosis (DKA) is an acute and life-threatening situation that accounts for the majority of diabetesrelated morbidity and mortality in children and adolescents who suffer from type 1 diabetes mellitus (T1DM). Objectives: To investigate the demographic, clinical characteristics, and outcomes of DKA in young patients with established T1DM and newly diagnosed diabetes in a tertiary referral hospital. Methods: Data from all T1DM patients diagnosed with DKA episodes in the pediatric endocrine unit at Besat university hospital, Hameden, Iran during 2006 -2013 were reviewed in a retrospective study. The data collected includes the demographic data (age, sex, place of residence, first presentation and established T1DM), clinical presentation (main presenting symptoms, average duration of presenting symptoms before hospitalization, precipitating factors, severity of DKA, level of consciousness), laboratory parameters (blood sugar, arterial blood gases, urine ketones, serum electrolytes) and the outcome. DKA was defined as a glucose level higher than 250 mg/dL, pH < 7.30, bicarbonate > 15 mmol/L and ketonuria. Data was entered and analyzed on SPSS version 16. A P value less than 0.05 were defined as statistically significant. Results: The study population comprised 72 children satisfying the inclusion criteria of the study. Mean age of patients was 9.4