Objectives: The purpose of this study was to compare the effect of phosphoric acid, one-bottle adhesive and self-etching adhesive on shear bond strength (SBS) of light-curing sealant to ungrounded primary and permanent enamel.Methods: In this in vitro study 30 primary molars and 30 permanent premolars were cleaned and divided to 6 groups (n=10). The following materials used on flattest, peripheral surface (mesial or distal) of permanent (groups 1,3,5) and primary (groups 2,4,6) teeth. Group 1&2 (control): acid etching + light-Curing sealant (Concise 3M-ESPE). Group 3&4 (SB): acid etching +2 layer bonding agent (Single Bond 3M-ESPE) + sealant. Group 5&6 (PLP): self etching adhesive (Prompt L-Pop 3M-ESPE) +sealant. The teeth were thermocycled 500 cycles between 5„a and 55„a with a dwell time of 30s. For shear bond strength testing, the load was applied vertically from the Zwick universal testing machine with load cell 10KN to the base of the mold at a cross-head speed of 5 mm/min. Then two way variance analysis (Between-Subject Effect) and multiple comparisons (Post Hoc Test-LSD) were performed. Failure mode was determined in a stereomicroscope at x20. Result: There was no significant difference in SBS between control (1&2), and PLP (5&6) groups, neither between SB (3&4) and PLP (5&6) groups (P>0.5). But there was significant difference in SBS between control and SB (3&4) groups (P=0.22). However, the SBS to primary enamel were lower than those to permanent enamel (P<0.5). Conclusion: The self-etching adhesive Prompt L-Pop, is as effective as conventional acid-etching in mediating a bond between a light-curing sealant and ungrounded human enamel. Applying Single Bond adhesive under fissure sealant would be beneficial for increasing the bond strength.