The aim of this study was to investigate serum levels of cortisol and adrenocorticotropic hormone in adolescents with first-episode early onset schizophrenia. A total of 23 adolescent patients, who did not receive prior therapy and who were diagnosed with psychosis according to DSM-IV, were included. Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version, Positive and Negative Symptom Scale, and Clinical Global Impression Scale were conducted with the participants. No significant differences were found between the patients and the control subjects in serum cortisol and adrenocorticotropic hormone levels (P>.05). Our study's findings do not support the hypothesis of increased hypothalamic-pituitary-adrenal axis activity in first-episode early onset schizophrenia.