Background: Previous research evidences have shown that group training of spiritual positivism reduces mental symptoms. Objectives: The aim of the present study was to determine the effectiveness of spiritual positivism training on reduction of the symptoms of depression, anxiety, and stress in prisoners. Methods:The statistical sample consisted of 30 inhabitant prisoners in Doroud city prison that were selected randomly for this study and divided to two groups (15 prisoners in the experimental group and 15 prisoners in the control group). Prisoners in the experimental group were trained for spiritual positivism during 10 sessions. Before and after the intervention and at the fallow up stage, they filled the questionnaire of DASS -21. Results: Results of repeated measure; mixed between within subjects analysis of variance indicated that training for spiritual positivism had a significant effect on the reduction of depression, anxiety and stress symptoms in prisoners. Conclusions: According to the obtained results, it can be suggested that the training of spiritual positivism can be applied as a useful method to reduce the symptoms of depression, anxiety, and stress in prisoners.