Pendahuluan: Streptococcus mutans (S. mutans) merupakan bakteri yang mempunyai glukosiltransferase surface (GTFs) yang berperan pada proses perlekatan dan virulensi bakteri pada permukaan gigi. Enzim GTFs terdiri atas tiga jenis enzim GTFs yaitu GTFB, GTFC dan GTFD dan masing-masing enzim ini dikode oleh gen gtfB, gtfC dan gtfD yang juga berperan sebagai prekursor dalam adhesi seluler plak gigi yang dapat menyebabkan karies gigi. Tujuan penelitian adalah mengidentifikasi gen gtfC dan gtfD S. mutans pada pasien karies gigi. Metode: Penelitian dilakukan dengan consecutive sampling. Sampel penelitian diambil dari kerokan jaringan karies gigi, diisolasi, dikultur, dan diidentifikasi di laboratorium Mikrobiologi dan Sentral FK UNRI. Identifikasi S. mutans dan gen kariogenik gtfC dan gtfD menggunakan metode Polymerase Chain Reaction (PCR). Data ditampilkan dalam bentuk tabel distribusi frekuensi dan dinyatakan dalam persentase Hasil: Dari 60 kerokan jaringan karies didapatkan S. mutans sebanyak 10 isolat, sedangkan gen gtfC dan gen gtfD didapatkan masing-masing 4 (40%) isolat. Simpulan: Gen kariogenik teridentifikasi gen gtfC dan gtfD pada isolat S. mutans dari pasien karies gigi sebanyak 40%.Kata kunci: gtfC, gtfD, kariogenik glukosiltransferase Streptococcus mutans. ABSTRACTIntroduction: Streptococcus mutans (S. mutans) is a bacterium with a glucosyltransferase (Gtfs) surface, which plays a role in the attachment process and bacteria virulence on the tooth surface. The Gtfs enzyme consists of three types of Gtfs enzymes, namely GtfB, GtfC, and GtfD. These enzymes are encoded by the GtfB, GtfC, and GtfD genes, which also act as precursors in the cellular adhesion of dental plaque that can cause dental caries. This study was aimed to identify the GtfC and GtfD of S. mutans in dental caries patients. Methods: This study was conducted with consecutive sampling. Research samples were taken from dental caries tissue scrapings, isolated, cultured, and identified in the Microbiology and Central Laboratory of the Faculty of Medicine University of Riau. Identification of S. mutans and GtfC and GtfD cariogenic genes using the Polymerase Chain Reaction (PCR) method. The data was displayed in the form of a frequency distribution table and expressed as a percentage. Results: From 60 caries tissue scrapings, ten isolates were obtained, while the GtfC gene and GtfD gene were obtained 4 (40%) isolates each. Conclusion: Forty percents of S. mutans isolates from dental caries patients were identified as the GtfC and GtfD cariogenic genes.Keywords: GtfC, GtfD, cariogenic, Streptococcus mutans glucosyltransferase.