The purpose of this study was to evaluate if the use of a disinfectant agent before the application of glass ionomer to dentin, affects its bond strength. 30 human teeth were embedded in acrylic and polished until mid-dentin was exposed. Glass ionomers used were: Vitremer (3M-ESPE), Ketac Molar (3M ESPE) y Fuji IX (GC America) (n=10). Half of the samples of each Group received Ultracid F (Ultradent products Inc.) for 20 before been washed with abundant water. Glass ionomer was applied after that. Samples were stored in water at 37o C for 7 days before been tested in shear in an universal testing machine at a crosshead speed of 0.01 cm/min. Vitremer had bond strengths ranking from 4.8 to 5.2 MPa, Fuji IX from 3.3 to 3.5 and Ketac Molar from 2.5 to 2.6 MPa. No significant difference was found between bond strengths to dentin with and without the application of the cavity disinfectant.