-Background and objectives:Various clinical aspects of Major Depressive Disorder (MDD) are related to the neuropsychological impairments characteristic of this illness. The aim of this study was to determine the relation between certain clinical variables of MDD -in particular the presence of comorbid anxiety disorders -and the neuropsychological performance of patients with MDD selected for a clinical trial.Methods: Using cluster analyses, we generated two groups of patients: one group with Major Depressive Disorder and a Comorbid Anxiety Disorder (MDDAD), and the other 6 IXCHEL HERRERA-GUZMÁN ET AL.