Objectives: This study aimed to evaluate the three and six month clinical and demographic outcome predictors (recurrence rate, the rate of hospitalization, severity of illness and recovery rates) in a group of children and adolescents with type I bipolar disorders. Method: The participants of this longitudinal and prospective study were 80 children and adolescents admitted in Roozbeh Hospital, Tehran, Iran with a diagnosis of type I bipolar disorder. Consecutive referrals were included in a prospective cohort. The participants were evaluated at admission, discharge, and follow-up at 3 and 6 months, using demographic questionnaire, Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version-Persian Version (K-SADS-PL-PV), Young Mania Rating Scale (Y-MRS), Children Depression Inventory (CDI), Beck Depression Inventory (BDI), and Clinical Global Impression (CGI). The Pearson correlation coefficient and multivariate regressions were used for data analysis. Results: The 6-month follow-up showed that there was a positive correlation between the severity of mania with male gender (p=0.01) and the severity of mania at admission (p=0.04). The rate of recurrence at the 6-month follow-up was correlated (p=0.05, r=0.22) with psychosis at admission. The duration of untreated disorder (p=0.03) had a positive correlation with the severity of global impairment at the 6 month follow-up. Conclusion: This study confirms the role of some demographic and clinical features in predicting the course of disease and response to treatment.