Stigma against people living with HIV (PLWH) seriously affects their quality of life. Moreover it can lead them to hide their HIV status from others, which in turn endangers public health. Many studies dealing with HIV-related stigma focus on the consequences of this phenomenon and pay less attention to the social conditions which affect different types of HIV-related stigma (anticipated, internalized and enacted stigma [ES]). Therefore, in this study, we tried to achieve more understanding about effective causal conditions of various types of experienced stigma. First of all, data were collected from 19 PLWH, using semi-structured interviews from those who had visited the Counseling Center for Behavioral Diseases in Mashhad. Secondly, the data were analyzed by applying a mixture of two methods: thematic analysis and qualitative comparative analysis (Boolean Algebra). The analysis of the data reveals that a combination of informing family members about HIV status, lack of family support, and medical support lead to anticipated stigma; a combination of religious beliefs and poor self-esteem results in internalized stigma and a combination of lack of family support, mistreatment by community, poor self-esteem, poverty and no religious beliefs lead to ES.