Adherence to antiretroviral therapy (ARV) is the key to suppressing the development of HIV disease, reducing the risk of drug resistance, improving overall health, improving quality and survival and reducing the risk of HIV transmission. A mother must comply with ARV therapy to prevent transmission from mother to child. Loss to follow up with antiretroviral (ARV) drugs in mothers can increase the risk of HIV transmission from mother to child. This study aims to ascertain the determinants of loss to follow up of HIV pregnant women taking ARV therapy in Preventing Motherto-Child Transmission (PMTCT) at the Jayapura Regional General Hospital. This research uses a qualitative method with a case study approach. Data collection was carried out through in-depth interviews, observation, focus group discussions (FGD), field notes and documentation with 7 HIV pregnant women who were recorded as not compliant to undergo ARV therapy. Data analysis was performed descriptively using triangulation and content analysis methods. The results of this study reveal that the determinants of loss to follow up with ARV therapy are low vulnerability and perception of illness, the presence of stigma and discrimination that is still high and low social support. With the results of the above study, one conclusion is drawn that the determinants loss to follow up of pregnant women with ARV therapy will add many new cases of HIV in Papua. So that if it is not handled better, then the Three Zero target in 2030 will only remain a discourse