The flexure strength of three resin-modified glass ionomer cements and one conventional glass ionomer cement and their bond strength to dental composites were studied by measuring the three-point bending and the shear strengths. The bond strengths between the dental composite and the resin-modified glass ionomer cements were dependent on the curing modes. Resin-modified glass ionomer cements bonded significantly more strongly to cured dental composites than dental composites bonded to cured resin-modified glass ionomer cements. However, the dental composites showed a significantly stronger bonding to the resin-modified glass ionomer cements than to the cured conventional glass ionomer cement, to which the dental composite did not adhere without acid etching. The flexure strengths of the resin-modified glass ionomer cements were significantly improved compared with the conventional one but were still significantly lower than that of the dental composites.