The detailed information about neuroanatomical alterations in adolescents with first-episode drug-naïve major depressive disorder (MDD) is still unknown. We measured cortical thickness, surface area and volume in 35 MDD patients and 22 healthy controls (HC). The MDD group, compared to HCs, showed reduction in cortical volume of the right precentral gyrus. We also found that MDD severity significantly correlated with cortical abnormalities in a number of regions, primarily in frontal and parietal lobes. These regions are implicated in emotion processing whose abnormities will contribute to the affective and cognitive dysfunction in adolescents with MDD.