Background: HIV/AIDS is an immunosuppressive condition often accompanied by other health problems, including fungal infections such as oral candidiasis. This infection is caused by Candida albicans, an opportunistic pathogen that commonly affects immunocompromised patients. Vitamin D is a vitamin which plays a key role in immune regulation and mucosal defenses, and deficiency has been linked to increase in opportunistic infection. Objective: This study aims to review relevant literature to determine the relationship and effect of vitamin D deficiency in HIV/AIDS patients with oral candidiasis. Methods: Research was conducted on PubMed, ScienceDirect, and Google Scholar using predetermined keywords and the results were limited to articles published in 2015-2025. Discussion: Vitamin D is an important immunomodulator that regulates innate and adaptive immune responses through vitamin D receptor (VDR) signaling in immune cells. Vitamin D deficiency is common in people living with HIV and is associated with increased immune activation, disease progression, and susceptibility to opportunistic infections. Through reviewing relevant literature, findings suggest that adequate vitamin D status may play a protective role against oral candidiasis and other opportunistic infections in HIV. Conclusion: Existing studies suggest that vitamin D deficiency may be an important factor in the occurrence of oral candidiasis in HIV patients. However, more research is needed to sufficiently establish a significant correlation between the two conditions.