Objectives: One of the goals of endodontic treatment is the adequate filling of the root canal, which is often done using gutta-percha and sealer. It has been reported that sealer remnants in the coronary pulp chamber cause tooth colour changes. Therefore, this study was designed to examine the effect of endodontic sealer remnants on tooth colour, testing the hypothesis that sealers cause coronal colour changes. Methods: Forty single-rooted human teeth were endodontically treated leaving excess sealer material in the coronary pulp chamber. The specimens were divided into four groups (n = 10) according to the endodontic sealer used (AH, AH Plus; EF, Endofill; EN, endométhasone N; and S26, Sealer 26). Teeth were stored at 37 °C moist environment. Colour coordinates (L*a*b*) were measured with a spectrophotometer before endodontic treatment (baseline-control), 24 h and 6 months after treatment. L*a*b* values were used to calculate colour changes (ΔE). Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney-U tests. Results: Colour changes were observed for all groups with S26 and EN producing the greatest mean ΔE values after 6 months. Conclusion: Endodontic sealer remnants affect tooth colour confirming the experimental hypothesis. Clinical significance: This study examined the effect of endodontic sealer remnants on tooth colour, and observed that after 6 months, the sealers produced unacceptable colour changes. © 2012 Elsevier Ltd. All rights reserved.