Objective. The aim of this study was to evaluate the cytotoxic potential of a type of endodontic pin on L929 cell line according to the UNI EN ISO 10993/2009 rule. Methods. L929 cells were used for the assays; extracts were prepared from three different-diameter endodontic pins, made of epoxy resin and fiberglass matrix and from Reference Materials (ZDEC, ZDBC, and HDP films). MTS assay was performed after 24 h, 48 h, and 72 h of exposure of L929 cells to pin and Reference Material extracts, 5% phenol solution, and control reagent. Cells cultured with different media containing extracts were monitored for up to 72 h and stained with haematoxylin/eosin. Results. Pins of different diameters had no cytotoxic effects on L929 cells at 24 h, 48 h, and 72 h (all values >70%). Cells cultured in medium containing pin extracts grew without any differences compared to the control cells. Conclusion. The endodontic pins tested showed no cytotoxic effects and did not induce changes in morphology for up to 72 h.