The paper introduces the mechanism of neuroplasticity, specifically the ability of the brain to develop new neurons (neurogenesis) and new connections between nerve cells (synaptogenesis) and to develop glial cells. The author presents the evidence proving the existence of neuroplasticity by giving examples of people with serious brain damage who function normally and, above all, of people living with almost no brain or with one hemisphere, or with post-stroke defects. However, the main purpose of this paper is to present the current state of knowledge of the importance of the brain plasticity for the course of psychotherapy, as well as for assessing its effectiveness. The author gives many examples which seem to lend credence to the proposition that recognized psychotherapies (mainly psychodynamic, interpersonal, and cognitive-behavioral ones) actually alter the brain in patients beneficially suffering from obsessive-compulsive disorder, schizophrenia, depression, or panic disorder. These changes most frequently occur in the amygdala and the caudate nucleus (responsible for emotions and learning), the hippocampus (responsible for memory and spatial orientation) and the prefrontal cortex (responsible for planning and behavior modification). The final part of the paper comprises the content concerning the pharmacological support of the cognitive behavioral therapy aimed at "plasticizing" memory taking “erasing” traumatic memories into consideration.