In this paper, we review the literature about the theory of mind (ToM) deficits in patients with bipolar disorder. According to several studies, bipolar patients have remarkable ToM deficits not only in manic and depressive periods, but even in remission. However, results on the association with the symptom severity and basic neurocognitive (especially executive) functions are controversial. Taken together, ToM deficits seem to be state dependent trait markers of the bipolar disorder. Some authors suggest that ToM deficits can influence the functional outcome. Therefore, the better understanding of ToM deficits in bipolar disorder is of particular importance. In the second part of the paper we review the methodological issues, and provide a possible guideline for the study of ToM in bipolar disorders. Illness specific considerations of the neuroimaging research, the ToM task used in the experiment, the experimental design, and the data analysis are particularly emphasized.