In this study, the cytotoxicity of commonly used local anesthetics was evaluated on odontoblasts which are essential for pulpal homeostasis in vitro. Local anesthetics, such as articaine, bupivacaine, levobupivacaine, lidocaine, mepivacaine, prilocaine, and procaine, were tested on the odontoblast cell line, MDPC-23. The concentration-and time-dependent cytotoxic effects of local anesthetics on odontoblasts were measured by MTT assay. Among local anesthetics treated for 18 h, only bupivacaine significantly showed cell death in a concentration-(LC₅₀=1.2mM) and time-dependent manner. To confirm cell death induced by bupivacaine, the observation of cell morphology and FACS using Annexin V and propidium iodide (PI) staining were performed. As a result of Annexin V and PI staining, as well as the morphological change, only bupivacaine induced apoptotic cell death on odontoblasts when compared with levobupivacaine and lidocaine. These results suggest that bupivacaine might affect normal pulpal integrity even after uneventful local anesthesia.