The goals of this study were to investigate differences in neurocognitive performance between groups of patients with unipolar major depressive disorder (MDD) or bipolar I disorder (BD-I) in a euthymic state, and to analyze associations among cognitive performance, sociodemographic and clinical variables, and global functioning. The study evaluated 25 outpatients with MDD and 25 outpatients with BD-I. Controls consisted of a sample of 29 healthy adult volunteers. All of the subjects were administered a battery of neuropsychological tests (Babcock Story Recall Test, Wisconsin Card Sorting Test, Trail Making Test Part B, Stroop Color and Word Test, Symbol- Number Association Test, and Digit Span). Patients demonstrated reduced performance on tasks involving executive functions (Trail Making Test Part B and Wisconsin Card Sorting Test) and attention (Digit Span and Symbol-Number Association Test) compared with healthy controls. Performance on neurocognitive tasks did not differentiate patients with MDD from those with BD-I. Improved performance on tasks that assessed executive functions by patients with BDI and MDD, considered as a single group, was associated with better global functioning, even when controlling for several sociodemographic and clinical confounders. Patients with MDD and BD-I showed a similar profile of information-processing deficits and similar global functioning. Global functioning was also moderately associated with performance on executive function tasks.