Candida albicans, a yeast frequently occurrent in dental plaque and able to secrete both organic acids and collagenolytic enzymes, is supposed to be involved in the caries process. The aim of the investigation was to prove the ability of Candida albicans to produce caries-like lesions in enamel and dentin in vitro. Specimens of enamel and dentin were contaminated with C. albicans strain SC-5314 and incubated in an artificial mouth. Controlled by a microcomputer, an artificial saliva with alternate amounts of carbohydrates was added. The purity and the pH of the culture were observed. After eight weeks of incubation, dentin specimens were embedded either in epoxy resin or in paraffin after decalcification. Five-micrometer-thick step serial histological sections were cut perpendicular to the tooth surface, stained with PAS, Goldner's and von Kossa's stain, and subsequently examined under the light microscope. Enamel slices of 150 micrometer thickness were inspected by polarized light microscopy. A deep demineralization due to organic acids produced by the yeast was found in both the enamel and the dentin specimens. Budding cells and hyphae of C. albicans penetrated the dentin by invading and enlarging the dentinal tubules. Sections of the samples stained with Goldner's stain revealed a loss of collagen close to the yeast, what seemes to be caused by collagenolytic activity of the Candida cells.The present investigation shows the ability of C. albicans strain SC-5314 to invade and destroy inorganic and organic parts of dental hard tissues. Further research is required to determine the role of Candida albicans in the pathology of dentinal caries. Schlagwörter: microbiology, candida albicans, artificial mouth