Background: Oral candidiasis is an opportunistic fungal infection that leads to acute and chronic infections in the mouth and gastrointestinal tract. According to studies, common antifungal drugs have some side effects and sometimes fail in Candida albicans candidiasis infections. Objectives: This study aimed to compare the efficacy of Aloe vera to that of nystatin on oral Candida species in vitro. Methods: This laboratory study was prepared in vitro from a collection of fungi and bacteria in Iran. The measured inhibitory concentration was within the range of 1:1 to 1:2048. The data were analyzed using SPSS software (version 24). Results: In C. albicans species, the inhibitory concentration of Aloe vera gel was 312.5 μL/mL. The inhibitory concentrations for Candidaglabrata and Candidatropicalis were 1250 and 625 μL/mL, respectively. In all groups, there was a significant relationship between Aloe vera and nystatin. Conclusions: Aloe vera gel showed antifungal properties in all tested species. The inhibitory concentrations of Aloe vera were much higher than nystatin. Therefore, to use this plant for humans, the concentration of its toxicity to humans should be estimated beforehand to avoid possible harm.