The phenomenon of impaired illness insight (anosognosia) often occurs after damage to or illness of the brain. As a result, affected patients can no longer adequately perceive existing disturbances (e.g., paralysis, memory disorders) that are obvious to everyone else. They overestimate their capabilities, and apparent difficulties in daily life are ignored, trivialized, or completely denied. For a nuanced understanding of the phenomenon and the psychopathology of the affected patients, it is important to consider not only the neural mechanisms but also psychological concepts (such as self-concept, metacognition, and self-reflection) and integrate these into a comprehensive theory of disorder and treatment. Only in this way can the behavior of the affected patients ultimately be understood.