Objective: To evaluate and compare shear bond strength and marginal leakage of a new self-etch sealant to enamel of human permanent teeth versus those of a conventional sealant. Method and Materials: Forty-four premolar crowns were mounted to expose flat lingual surfaces and randomly assigned to 1 of 2 test groups: conventional sealant (group 1, control) and self-etch sealant (group 2). Sealants were expressed into hollow plastic cylinders placed on the mounted teeth and polymerized according to manufacturers' instructions. Shear bond strength was measured at a crosshead speed of 0.5 mm/min. Another 44 premolars were randomly assigned to either group 1 or group 2 for microleakage testing. Sealants were applied to the occlusal groove as per manufacturers' instructions, and specimens were thermocycled, stained, sectioned, and examined for marginal leakage. Results: The bond strength of conventional sealant to enamel was significantly (P .05) higher than that of self-etch sealant. The conventional sealant showed significantly (P .05) lower microleakage than the self-etch sealant. Conclusions: Pending clinical validation, the new self-etch sealant under investigation provides lower bond strength and greater marginal leakage than the control (sealant application following standard acid etching). Keywords: enamel bond strength, microleakage, sealants, self-etch adhesive