Hierarchical psychopathology contributes to providing a broader picture of the links between emerging personality structures such as the DSM-5/ICD-11 trait models and clinical disorders. The present study aimed to predict the specific and general clinical symptoms by the less studied constructs of the ICD-11 model (negative affectivity, detachment, dissociality, disinhibition, and anankastia). Data from 642 young adults from Iran (63% female, 18-34 years) were collected by three mental symptom scales and the Personality Inventory for DSM-5 (PID-5), which was recently used to harmonize the constructs of the DSM-5 and ICD-11 trait models. Multiple linear regressions showed that the ICD-11 model significantly predicted both the specific clinical symptoms (ranging from R 2 = 0.15 to 0.40) and the general factor of clinical symptoms extracted by exploratory factor analysis (R 2 = 0.40, all p < 0.001). Negative affectivity was the strongest construct correlated with both the specific symptoms (ranging from β = 0.36 to 0.69) and the general symptom factor (β = 0.59, all p < 0.001). Because the ICD-11 trait model is a practical structure related to the clinical psychopathology in young adults, screening for maladaptive traits can help clinicians in case formulation for diagnosis and treatment.