Aim: Intracanal medicaments are often recommended during endodontic sessions to eliminate the necrotic debris and microorganisms. The aim of the present study was to observe the cytotoxicity of calcium hydroxide (CH) and colchicine (COL), at different concentrations, on human gingival fibroblast cells.Materials and Methods: Human gingival fibroblasts were cultured on plastic flasks containing RPMI 1640 media and fetal calf serum 10% supplemented with antibiotic agents. Trypsin/ethylenediaminetetraacetic acid 0.2% enzyme was used to isolate the cells, and the suspension was transferred to tubes for centrifuging. Conventional CH and COL were separately mixed with sterile saline solution to prepare a stock media. By serial dilution of stock media, desired concentrations were prepared at 2, 1.75, 1.5, and 1.25 mg/ml, separately. After considering a control group, the cells were exposed to test materials. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was conducted at 24 h, 72 h, and 7 days later. Optical density (OD) was evaluated to attain cell viability percentage. Finally, the recorded data were analyzed by Kruskal–Wallis and Mann–Whitney tests using SPSS software version 19 at a significant level of 0.05.Results: The highest (1.40 ± 0.66) and lowest (0.15 ± 0.00) ODs were observed in CH 1.25 mg/ml and COL 1.5 mg/ml after 72 h, respectively. All of the concentrations of both CH and COL showed significant OD differences with the control group (all P = 0.001).Conclusion: Both CH and COL manifested similar cytotoxicity on human gingival fibroblast cells.