Background: People with mental and behavioural disorders have low satisfaction of quality of life, due to numerous symptoms, as well as poor interpersonal relations, communications skills, low tolerance on frustration.Aim: The aim of this paper was to evaluate whether there has been an improvement in satisfaction with the quality of life after the application of group therapyMethods: The study included 100 patients who attended group therapy, for a period of 6-12 weeks. The instruments used at the beginning and at the end of the treatment were Outcome Questionnaire-45 which measured symptoms distress, interpersonal relations, and social roles, and MANSA questionnaire that measured satisfaction with the quality of life. Results: In total sample (N = 100) there was approximately equal number of women and men (51% vs. 49%). The average age of the subjects was 48.11 ± 7.91. Majority of respondents had depressive disorder (45%). Measuring the mean values obtained on the OQ-45 questionnaire, it was found that after the application of group therapy a significant reduction of the level of dysfunction was achieved. A statistically significant difference was found in the areas of satisfaction with physical and mental health, and the overall score of the MANSA questionnaire.Conclusion: Results show that patients reported lower symptoms distress and higher satisfaction with quality of life after attending group therapy, better interpersonal relations, lower risk of suicidal behaviour and substance abuse. Group therapy is successful intervention which helps patients improve quality of life.