There has been influx of official development assistance (foreign aid) into the health sector in Nigeria but little or nothing is known about the impact of such funds on specific health outcomes in Nigeria. Given the economic implication of HIV/AIDS, this study therefore assessed the effect of health aid on the prevalence of the HIV/AIDS in Nigeria. Relevant data spanning 1990 to 2017were sourced from World Development Indicator (WDI) and Organization for Economic Cooperation and Development (OECD) database and analyzed within the Autoregressive Distributed Lag (ARDL) framework. Model estimation results revealed that health aid had no significant effect on HIV prevalence in the country. Effective utilization of health aid was advocated in order to reduce the HIV prevalence rate thereby reducing the accompanying burden on the people and the economy.