According to the Diagnostic and Statistical Manual of Mental Disorders (DSM IV-TR, 2000) we cannot diagnose Generalized Anxiety Disorder (GAD) in bipolar patients, when it occurs exclusively during a Mood Disorder regardless of illness phase. In fact, Issler et al. (2004)1 have reported that some researchers criticize DSM diagnosis criteria for distinguishing these disorders, because in GAD there are criteria that overlap with those of bipolar disorder (BD). Recently, Goodwin and Jamison in their Comorbidity Chapter of second edition Maniac Depressive Illness Book (2007) did not describe anything about GAD when they reviewed the comorbidity of bipolar and anxiety disorders. However, despite these milestones that transform diagnosing of anxiety disorder in bipolar patients to a difficult task, several studies have reported the feasibility of diagnosing the presence of GAD in BD. In fact, several studies have found a higher prevalence of GAD in bipolar patients than in the general population. Albert et al. (2008) have evaluated anxiety comorbidity in euthymic bipolar patients and shown that the current and lifetime prevalence of GAD in euthymic patients is 15.2% and 16.2%, respectively. So, the question is: If the diagnosis of GAD in bipolar patients is not possible to be made, how can we explain the prevalence of GAD in euthymic patients through the SCID-I? Besides that, if the presence of GAD in 15.2% of euthymic patients was detected, what is the true significance of this rate? Do patients in a euthymic phase actually have GAD as a comorbid condition or is this in fact just a subthreshold presentation of BD? We would appreciate hearing your opinion about the presented issues regarding the role of GAD in each BD phase and the reliability and feasibility of performing a comorbid diagnosis in bipolar individuals. Finally, it would be interesting to study not only the overlapping characteristic but also the boundaries between GAD and BD in order to determine whether distinguishing anxious symptoms from GAD in bipolar patients in feasible and clinically relevant.