Introduction. The Cognitive dysfunction in bipolar patients has been described during affective episodes, recently there also has been published information regarding this impairments during euthymia. Aim and Objectives. This is a two phase study, Phirst phase corresponds to the descriptive phase of Cognitive function in Bipolar I euthymic subjects, Second phase will be the comparison of cognitive function between euthymic bipolar individuals vs. healthy controls. Methods. We report here the results of the phirst phase, which obtained descriptive data regarding cognitive function in Bipolar I subjects during euthymia. We applied DSM-IV interview (SCID-I)to assess psychopathology in healthy subjects and confirm BD diagnosis and subtype. The total sample complete a battery of scales formed by Hamilton Depresión rating scale, Young Mania rating scale, London Tower and the TAVEC (Spanish-Complutense Verbal Learning Test). Results. Descriptive data showed that Bipolar I individuals even in euthymia had impairment in executive functions. We found an association of depressive, mixed and psychotic depressive episodes with dysfunction in right dorsolateral prefrontal cortex. Verbal fluency didn´t showed any impairment, and reflected integrity of the hippocampal complex. Executive control related with frontal lobe function was impaired. Conclusions. Subjects with Bipolar Disorder I even in euthymia have impairments in executive functions. More research is needed to understand the underlying mechanisms related to the genesis of disease and to develop neuropsychological biomarkers for early diagnosis.