The purposes of this study were to investigate the prevalence of depression in pediatric thalassemic outpatients and to explore factors associated with depression. The subjects of this study included 370 pediatric thalassemic outpatients who were treated at hematology clinic, King Chulalongkorn Memorial Hospital, Siriraj Hospital, Phramongkutklao Hospital and College of Medicine, and Bhumibol Adulyadej Hospital,. These subjects ranged in age from 10-15 years old (x-=11.86 years). The research instruments consisted of Children and Parent Questionnaires, Children's Depression Inventory (CDI), and the Cornell Interview of Peers and Friends (CIPF). The data were analyzed by SPSS/PC+, Percentage, mean, and standard deviation were determined Unpaired t-test, One-way ANOVA, Chi-square test, Fisher's exact test and Stepwise multiple regression analysis were used fro statistical analyses. The study found that the prevalence of depression in pediatic thalassemic out patient was 35.1%. The Chi-square test and Fisher's exact test indicated the following essential factors: parents relationship (p<.01), relationship with family members (p<.01), peers relationship (p<.01), grade report (p<.01), child abuse history (p<.05), and mother's education level (p<.05). Statistically significant factors related to severity of depression in these children were sex (p<.01), time of onset (p<.01), parent relationship (p<.01), peers relationship (p<.01), grade report (p<.05), child abuse history (p<.05), mother's education level (p<.05), and relationship with family members (p<.05). In this study a forecasting equation was constructed from stepwise multiple regression analysis. The best predictive variables were peers relationship grade report, and child abuse history. From this equation, the best factor that can predict depression was peers relationship, predicting about 35.6 percent (R2=.356)
