In the paper, new information on diagnosis and treatment of affective illnesses and schizophrenia is presented. Regarding affective illnesses, the results of contemporary studies on the recognition of bipolar affective disorders, the use of mood-stabilizing drugs and treatment of depression, especially drug-resistant depression, are discussed. In schizophrenia, the evolution of target symptom treatment of schizophrenia, current neurodevelopmental theory and the role of introducing second generation antipsychotic drugs for treatment of the disease are presented. Special attention has been paid to the studies carried out in Poland, especially in Poznań. In the final part of the paper, the results of contemporary molecular-genetic and psychopharmacological studies are discussed, undermining the dichotomous concept of the division of psychiatric disorders that was proposed by Emil Kraepelin 110 years ago.