Purpose: The use of reinforcing fibers in dentures has raised concerns about possible increased adherence of yeasts t o the surface. The aim of this in vitro study was to compare the adherence of Candida albicans to the surface of denture-base polymer and to E-glass fibers. Materials and Methods: Test specimens were made from an autopolymerized denture-base resin (Palapress) reinforced with preimpregnated unidirectional E-glass fibers, which were exposed at the surface. The test specimens were pretreated with parotid saliva and incubated without agitation in standardized yeast suspensions (10 to the eighth power colony-forming units per mL) in phosphate-buffered saline at 37 degrees C for 1 hour. The test specimens were then washed to remove nonadherent cells. After being air dried, they were sputter coated with gold-palladium for scanning electron microscopy (SEM). To compare the adherence to different surfaces, the num ber of yeast cells found either on the polymer matrix or on the glass fibers was counted from SEM fields (170 um x 120 um, 600x) of randomly selected areas. Results: The mean density of yeast cells found on the surface of the polymer matrix was significantly higher (P 0.001) than that on the surface of glass fibers. The number of adherent yeast cells found at the interface between the fibers and polymer matrix was high. Conclusion: The adherence of C albicans to E-glass fibers was lower than to polymer matrix in the denture composite. If fibers are exposed only during polishing of the composite, the reinforcing material appears not to increase the adherence of this common oral yeast. However, areas with permanently exposed fibers may provide mechanical retention for yeast cells at the interface of the components.