Saliva contamination is a major clinical problem during restorative dental treatment. Restorative systems must possess sufficient marginal sealing ability to avoid microleakage. PURPOSE: The purpose of this study was to investigate the effect of saliva contamination on the microleakage of cavities restored with Prime & Bond NT and Dyract-AP. METHOD: Cavities were prepared with occlusal margins in enamel and gingival margins in dentine on the buccal surfaces of extracted human permanent premolar teeth. The cavities were etched with phosphoric acid or a non rinse conditioner (NRC). Preparations were distributed randomly into 4 treatment groups (N = 18) consisting of two respective etching methods (phosphoric acid/NRC), each with and without saliva contamination. After the restorative process the samples were thermocycled in dye, sectioned, and scored for microleakage. RESULTS: Contamination with saliva had no significant effect on microleakage on the enamel or dentine sides where phosphoric acid was used as conditioner. Where NRC was used, significantly more microleakage was observed at the enamel sides, but significantly less at the dentine sides.