Introduction: HIV remains a significant global public health challenge, with substantial impacts on individuals, communities, and healthcare systems. In 2018, it was estimated that approximately 37.9 million people were living with HIV, including 1.7 million children. The global prevalence of HIV among adults was approximately 0.8%, with a substantial proportion of individuals (around 21%) unaware of their HIV-positive status (UNAIDS, 2019). Since the onset of the HIV epidemic, an estimated 74.9 million people have become infected with HIV, resulting in approximately 32 million deaths from AIDS-related illnesses (UNAIDS, 2019). However, there has been significant progress in reducing AIDS-related deaths, with a notable decline of over 55% in AIDS-related deaths since the peak in 2004 and 2010 (UNAIDS, 2019). Thus, this study aimed at investigating the prevalence of HIV exposed children testing at 18 months and factors affecting the uptake of these services in various clinics of Mansa district, Luapula province, Zambia. The main objective of the study was to evaluate the prevalence of HIV exposed children testing at 18 months and factors associated with the uptake of these services in various clinics of Mansa district in Luapula province. Method: An analytical cross-sectional research design was used for this study. The study population were HIV positive mothers who enrolled in PMTCT at the selected Clinics of Mansa District in Luapula Province. Simple random sampling method was used to select the respondents who were interviewed face to face using a pretested structured interview questionnaire. Data were analyzed using SPSS version 24. The t-test was used to assess statistical significance of associations between variables at significance level of 0.05 and 95% confidence. Furthermore, multiple logistic regression analysis was conducted to examine the relationship between the likelihood of HIV testing at 18 months (dependent variable) and various independent ........