Aims of the study: analysis of the impact of group psychotherapy on personality functioning of patients treated for neurotic disorders, and selected personality disorders; evaluation of the effectiveness of group psychotherapy; assessment of personality questionnaire MMPI-2 utility in the diagnosis, qualification for treatment and the process of monitoring the effectiveness of psychotherapy in patients suffering from neurotic and personality disorders.Results and conclusions: Symptoms of neurotic disorders and personality functioning disorders in the majority of patients at the beginning of therapy were significantly higher than in healthy population. A significant reduction in symptoms of neurotic disorders and in the severity of neurotic personality traits as well as positive change in personality functioning and increase of ego strength was observed in the majority of treated patients. The frequency of obtaining recovery was not significantly different between men and women. Female patients function in traditional feminine roles more frequently than male patients who are in the opposition to the traditional masculine roles more frequently before and after the treatment. Polish version of MMPI-2 is a useful tool in diagnosis and monitoring of the psychotherapy process of patients suffering from neurotic and personality disorders. Intensive short-term group psychotherapy is an effective, worthy of recommendation treatment method of neurotic disorders and selected personality disorders in women as well in men, leading in most patients to favourable changes in personality functioning.