Objective: To evaluate the effect of adhesive agents and fissure morphology on the microleakage and penetrability of pit and fissure sealants. Method and Materials: Sealants used in this study included Aegis (Bosworth), conseal f (Southern Dental Industries), and Admira Seal (Voco). Adhesive agents included Optibond Solo Plus (sds/Kerr) and Clearfil S3Bond (Kuraray). Ninety extracted permanent molars were randomly assigned to 9 groups combining sealant and adhesive agent materials. A sealant and control group (phosphoric acid etch only) was also included. Dye penetration (microleakage), penetrability, and fissure morphology assessment was performed for the treatment groups through microscopic evaluation. Results: Significant (P = .003) differences in microleakage were exhibited, with the Aegis + control and Aegis + Optibond Solo Plus groups displaying less leakage, while significant (P = .03) differences were also noted between groups regarding penetrability. Fissure morphology was not a significant (P = .82) factor affecting microleakage; however, fissure type did significantly (P .001) impact penetrability. No correlation was found between the extent of microleakage and penetrability. Conclusion: Application of sealants using phosphoric acid as a conditioning agent revealed superior results, while the use of adhesives was found to be unnecessary. Keywords: adhesive, fissure morphology, microleakage, pit and fissure sealant