Background: Non-traumatic coma is a common condition in children that may cause considerable morbidity and mortality. Determining the most common causes of loss of consciousness in any specific region, and any sex and age group will dramatically reduce mortality and morbidity. Objectives: The purpose of this study was to evaluate the most common causes of non-traumatic coma among children in south east of Iran. Patients and Methods: All children (aged 1 month to 15 years) hospitalized for non-traumatic coma were included in this study. All of the patients received clinical measures such as history, physical, and neurological examinations. Glasgow coma scale (GCS) was used to determine the level of consciousness and paraclinical examinations, including CBC with differential, blood biochemistry, urine analysis, and liver function tests were performed on all patients. In case of indication, blood and urine culture, brain CT (Computed Tomography) scan or brain MRI (Magnetic Resonance Imaging), lumbar puncture, metabolic study, EEG (electroencephalogram), and so forth were carried out. Finally, the data were analyzed and the most common causes of loss of consciousness were determined. Results: Among the 123 children under investigation, 76 cases were male (61.8%) and 47 females (38.2%) with the mean age of 3.2 ± 0.64 years. The most common causes of loss of consciousness among children were as follows: toxic causes in 61 patients (49.6%), infectious causes in 30 patients (24.4%), metabolic causes in 11 patients (8.9%), structural brain abnormalities in 4 patients (3.3%) and seizure in 7 children (5.7%). Moreover, 10 patients (8.1%) had other causes of loss of consciousness. Conclusions: Toxic causes with an incidence of 49.6% were the most common cause of loss of consciousness among all age groups.