Bipolar disorders are a group of psychiatric disorders with profound negative impact on affected patients. Even if their symptomatology has long been recognized, diagnostic criteria have changed over time and diagnosis often remains difficult. The Fifth Edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), issued in May 2013, comprises several changes regarding the diagnosis of bipolar disorders compared to the previous edition. Diagnostic categories and criteria for bipolar disorders show some concordance with the internationally also widely used Tenth Edition of the International Statistical Classification of Diseases and Related Health Problems (ICD-10). However, there are also major differences that are worth highlighting. The aim of the following text is to depict and discuss those.