INTRODUCTION: Oral candidiasis is an oral mucosal infection caused by sp. This infection can appear in patients with HIV/AIDS associated with immunodeficiency. Another factor that can aggravate the occurrence of oral candidiasis is the COVID-19 infection caused by the SARS-CoV-2 virus as a current pandemic condition. This case report aims to explain the mechanism of COVID-19 infection as a factor that can aggravate the condition of oral candidiasis in HIV/AIDS patients. CASE: A 56-year-old male patient was consulted from the COVID-19 isolation unit to the Department of Oral Medicine with complaints of sore and uncomfortable mouth related to white plaque covering the surface of the tongue. The patient was diagnosed with HIV/AIDS and had a COVID-19 infection. The management instructions were to maintain oral hygiene, administration of antifungal drugs such as nystatin oral suspension and fluconazole, chlorhexidine gluconate 0.2% mouthwash, and vaseline album. DISCUSSION: Generally, HIV/AIDS patient has dysregulation of the immune system which can suppress host immunity to fight pathogens, making it easy for opportunistic infections such as oral candidiasis. The COVID-19 infection can cause lymphopenia conditions that further reduce the host's ability to fight pathogens. The SARS-CoV-2 virus can also directly attack various tissues in the oral mucosa which can contribute to exacerbating the severity of oral candidiasis in HIV/AIDS patients. CONCLUSION: The COVID-19 infection is a factor that can exacerbate the condition of oral candidiasis in HIV/AIDS patients by further decreasing the host's immunity and damaging various tissues in the oral mucosa.