ABSTRACT Objective: We sought to compare differences in cognitive function between patients with bipolar disorder type 1 (BPD-1) and healthy controls (HC) and to investigate the relationship between cognitive functions and functional areas of patients with BPD-1. Methods: This study included 93 euthymic patients with BPD-1 and 64 healthy age- and sex-matched individuals. All participants completed a sociodemographic form; took the Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI), and Montreal Cognitive Assessment Scale (MoCA) assessments; and underwent a neuropsychometric battery. Results pertaining to the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, fourth revision Axis I Disorders (SCID-I), Young Mania Rating Scale score, and Bipolar Disorder Functioning Questionnaire score were obtained for the patients; the HC group was investigated using the SCID nonpatient version. Results: All of the cognitive domain scores were significantly lower in the BPD-1group than in the HC group (p < 0.05). A statistically significant positive correlation was observed between the neurocognitive domains of attention, verbal memory, visual memory, and BPD-1 total functioning (p < 0.05). Discussion: Impairments in verbal memory, visual memory, and attention among euthymic patients with BPD-1 may cause impaired functionality.