Informed consent and insight are among the most important issues in medical treatment, especially for psychiatric patients. In this study, we examined the competence to consent to psychiatric hospitalization of 113 psychiatric patients who were voluntarily admitted to a mental hospital in various psychotic states and compared it with their insight. We found a significant correlation between the patients' competence and insight into their illnesses. There is a discussion of the problematic issues of informed consent, competence and psychosis and the importance of insight in the context of mental illness.