OBJECTIVES The objective of this study was to examine the possible correlation between the strength of glass ionomers and their adhesive strength to metals. METHODS Three different brands of glass ionomers mixed at four different P/L ratios were evaluated. The compressive and diametral tensile strengths of the cements were determined. The shear bond strengths were determined between four different types of dental casting alloys and the cement made with the different P/L ratios. RESULTS Significant (p < 0.05) increases in the bond strength to any of the metal surfaces were found in the cement specimens mixed at the highest P/L ratio compared to those mixed at the lowest P/L ratio. For two glass ionomers (FI and DNT), the specimens prepared at the highest P/L ratio showed significantly greater diametral tensile strength than those prepared at the lowest P/L ratio (p < 0.05). SIGNIFICANCE The present study showed a significant correlation between diametral tensile strengths and bond strengths. It is suggested that the use of glass ionomers with high mechanical strength is an important factor of enhancing the adhesion to metal surfaces.