Purpose: The aim of this clinical study was to investigate the influence of salivary exposure on microtensile bond strength of one self-etching adhesive resin. Materials and Methods: Thirty carious premolars were divided into two groups: a rubber-dam was either inserted before or after cavity preparation and the cavities were restored using direct composite resin. After extraction, the teeth were sectioned into microbars and the microtensile bond strength (MTBS) test was conducted (a = 0.05). Scanning electron microscopy (SEM) and silver nitrate staining to detect nanoleakage were conducted to evaluate the sealing quality of the bonded interface. Results: Statistical analysis revealed that placement of rubber-dam before cavity preparation resulted in significantly higher MTBS values (24 ± 2 MPa) and predominantly cohesive failures (85%). SEM of specimens exposed to saliva revealed the presence of structural defects at the tooth/resin interface and pull-out of shorter resin tags. Silver nitrate nanoleakage confirmed these findings as well. Conclusion: It is recommended to insert a rubber-dam before commencing with cavity preparation in order to ensure strong and durable bond strength. Keywords: salivary contamination, microtensile bond strength, SEM