Ruta angustifolia is a medicinal plant often used in treating various diseases. Several studies have been carried out to reveal the chemical compounds in this plant, and some are effectively used as antimicrobials. Candida albicans is the most common pathogenic fungus in humans and causes many cases of infection. C. albicans can form biofilms on biotic and abiotic surfaces, either as mono or multispecies, that may increase its pathogenicity. In a state of forming biofilms, microbes are surrounded by an extracellular matrix that protects the microbial community from antimicrobial agents. In this study, we examined the effect of R. angustifolia extract on C. albicans biofilm formation. C. albicans preformed biofilms (24 h) were treated with various concentrations of R. angustifolia extract (100%, 50%, 20%) and incubated at 37°C for 24 h. The characteristics of biofilm formation were assessed with microscopic methods using a light microscope. The results indicated that the effect of R. angustifolia extract could inhibit the C. albicans hypha formation at all concentrations treated.