Mixed states are heterogeneous clinical entities difficult to define precisely. The stringent actual DSM IV criteria are unsatisfactory for current clinical use. Many frequently encountered mixed patients benefit without an accurate diagnosis from biological therapeutic interventions such as the introduction of mood stabilizers. We propose a brief review of the definition and characteristics of mixed states and propose a new approach to the typology of mixed states. Based on recent literature data, we add to the depressive and manic syndrome the concept of dysphoria as a third dimension. Integrating this three dimensional approach with recent factor analysis, we describe in addition to the DSM IV mixed state (type I) two new subtypes of mixed states (type IIM and IID). This new typology can give the clinician a more accurate understanding of the complex and polymorphous reality of mixed states and help him make more specific therapeutic interventions. These subtypes of mixed states will need validation through prospective clinical studies. Biological differences, differential outcome over time, and differential response to treatment will be important validation criteria.