In the first part of the article, two aspects of social cognition, such as the Theory of Mind (ToM), i.e. the ability to infer about mental and affective states of other people, having both cognitive and perceptive aspects as well as empathy, i.e. the ability to understand other person’s perspective and take an emotional response of the observer to the affective state of the other person, were presented. Next, research on social cognition in schizophrenia and bipolar disorder (BD) has been reviewed, and the disturbances, observed in these two illnesses were compared, with particular emphasis on studies investigating social cognition in both schizophrenia and BD. The results of studies show that ToM disturbances occur both in schizophrenia and BD patients, however, in schizophrenia they are of greater severity. As for empathy, patients with schizophrenia have significant disturbances of recognizing emotions, as well as of cognitive and affective empathy. Patients with BD do not have abnormalities in cognitive empathy, have lesser disturbances of emotion recognition disorder compared with schizophrenia and show a connection between disturbances of affective empathy and the course of the disease (time period after manic or depressive episode). Further exploration of these issues seems important in order to determine to what extent the disturbances of social cognition can influence social and professional life of patients. It is also a potential area for therapeutic interventions supportive to pharmacotherapy.