Objective: To analyze the marginal adaptation of two different Glass Ionomer Cements (GIC) after erosive challenges. Material and Methods: Sixty sound extracted primary canines were selected and class V cavities were made. Teeth were allocated into 6 groups according to restorative material: 1) high-viscosity GIC (Ketac™Molar Easymix) and 2) resin-modified GIC with nanoparticles (Ketac™N100), low pH beverage erosive challenge (Orange juice and Coca-Cola) or distilled water as control. Thereafter the sample was restored and subjecting to thermocycling. The sample was immersed for a 10-days period for the erosive simulation and then embedded in methylene blue solution during 4 hours. Finally teeth were sectioned for further analysis. Marginal adaptation test was performed by two trained examiners using the Salama et al. criteria. Descriptive and Kruskal-Wallis test (α=5%) were used to analyze the data. Results: The groups treated with Ketac™Molar EasyMix were similar in terms of marginal sealing ability when submitted to Orange juice and Coca-Cola but significantly worse than water. For samples restored with the Ketac™N100 the worst results were found in the Coca-Cola group. Conclusion: Erosive challenges with acidic drinks affected the marginal adaptation of the tested GIC.