A new fluoride-releasing sealant system is claimed to allow easier and faster placement while providing high bond strengths without the need for phosphoric acid etching. A study was designed to compare the microleakage and shear bond strength of a self-etching, Giomer-based sealant system with those of a traditional resin sealant. Group 1 received traditional sealant applied after use of a 35% phosphoric acid etchant; group 2 received Giomer sealant after use of a self-etching primer; and group 3 received Giomer sealant after the addition of an initial phosphoric acid etching step and placement of the primer. The sealants were placed in the occlusal pits and fissures of extracted human third molars, thermocycled, placed in dye, and sectioned. The extent of microleakage (dye penetration) was expressed as a percentage of the cross-sectional length of the sealed interface. The sealants were also bonded to the facial enamel of bovine incisors. Specimens were thermocycled and tested in shear mode in a universal testing machine. The new self-etching sealant demonstrated significantly greater microleakage (P < 0.017) and lower bond strength (P < 0.05) than both the traditional sealant system and the new system when placed with phosphoric acid etchant. Phosphoric acid etching significantly improved the shear bond strength and reduced the microleakage of the new sealant.