Objective:To evaluate the microtensile bond strength of total-etch or self-etch adhesives to caries-affected dentine versus normal dentine. Methods:Twenty-four extracted human molars with mesial coronal carious lesions extending into mid-dentin were selected. The softened carious dentine was removed with a slow-speed, carbon-steel bur and Caries Marker was used as guides. Prepared cavity in sound dentine in the distal coronal part of the identical teeth was used as the control. Surfaces were bonded with either Prime&Bond NT, Adper Single Bond 2, Adper Prompt or XenoⅢ,according to manufactures' recommendations. A crown was built up using resin composite(Filtek P60).After storage in water (37 ℃,24 h),teeth were vertically serially sectioned into 1.0 mm thick slabs and trimmed to yield 1 mm2 test area that contained either caries-affected or normal dentine. Then the specimen were tested in tension in an Instron machine at 0.8 mm/min.The bonding interface between the dentine and adhesives was qualitatively evaluated under the observation of scanning electron microscope(SEM). Results:Two total-etch adhesives yielded higher bond strengths than the two self-etching systems. And all the adhesives attained higher strengths in normal than in caries-affected dentine(P