BACKGROUND AND OBJECTIVES: Maintenance of pulpal health is a critical prerequisite for successful application of light amplification by stimulated emission of radiations (lasers) in the hard tissue management of vital teeth. The purpose of this study was to investigate the short- and long-term pulpal effects to cavity-preparations in healthy human teeth using erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser. MATERIALS AND METHODS: A total of seven healthy third molars that were to be removed due to space-problem were used. Following the laser excavation, the cavities in dentine were closed temporarily and the teeth were extracted after 7 days (n = 5) and 3 months (n = 2) post-operation. The specimens were fixed, decalcified, subdivided, and processed for light and transmission electron microscopy. RESULTS: In the short-term group, four of the five laser-drilled teeth did not reveal any pathological changes in the pulp-dentine complex. One tooth showed mild disruption of odontoblasts (OB) and vascular dilatation subjacent to the deepest point of the cavity-preparation with a remaining dentine thickness (RDT) of less than 80 microm. The two teeth under long-term observation revealed distinct apposition of tertiary dentine (TD), lined predominantly with cuboidal cells on its pulpal aspect. CONCLUSIONS: These results would allow a conclusion to be drawn that the Er:YAG laser under investigation is a pulp preserving hard-tissue drilling tool when used with the specific energy settings and emitting radiation at a wavelength of 2.94 microm.