The goal of the study was to examine the mental health of prisoners and to examine whether there are differences in the occurrence of anxiety, depression and stress with regard to demographic characteristics, the length of stay of the prisoners in the penitentiary, and whether there is a mutual connection in the occurrence of these mental disorders. A crosssectional survey was conducted among the prisoners of the prison in Požega during May and June 2020. The research included 74 prisoners (51.4% male) The age of the respondents was in the range from 18 to 78 years, the most respondents were from 31 to 40 years old, (35.1% of them). The Depression Anxiety Stress Scale (DASS21) questionnaire was used to assess the current level of anxiety, depression and stress. The results show that the majority of respondents have moderate depression (p=<0.001), severe (27%) and very severe anxiety (27%, p=0.171), while their stress level is normal (35.1%, p=.02). Anxiety is more common in female respondents (p=0.002). There is a moderate correlation between anxiety and the length of deprivation of liberty. The association between depression and anxiety is highly positive (p<0.001), while the association between depression and family relationships is low and positive. Respondents who are not married showed a higher frequency of depression (p=0.01). A higher level of stress was recorded in male respondents (p=0.02), married (p=0.04) and with a higher level of education (p=0.03). Mental health represents a serious public health problem within this population group and requires further attention and the need for more frequent screening and timely treatment.