Introduction: This study investigated the sealing ability of three different adhesives in primary bovine teeth. Methods: Facial and lingual class V cavities were prepared half in enamel and half in cementum, in 48 bovine primary mandibular incisors and randomly divided into three groups and each group divided to two subgroups. The tested adhesives were XPBond (XP), ClearfilS3 Bond (S3), and Xeno III (XE). All cavities were restored with composite and light cured. After 24 hours storage in 37°C distilled water and polishing, teeth were thermocycled and sealed with nail varnish. Then, they were stored in 2% methylene blue and dye penetration was evaluated under a stereomicroscope. Results: No significant differences were recorded in the microleakage value between three adhesives in enamel and dentin margins (p>0.0.5) before and after thermocycling. The lowest microleakage value was obtained in XE followed by XP and S3. Conclusion: There were not any differences between adhesives in enamel and dentin margins of class V cavities on primary bovine teeth.