Objective: This clinical study compared the clinical performance of a pit and fissure sealant placed with the use of different enamel preperationmethods, acid-etching or Er, Cr:YSGG laser application, over 18 months.Material and Method: Sıxteen subjects (15 female, 1 male) wıth no restorations or sealant present on the fissures and no detectable caries werepartıcıpated ın the study. Using a table of random numbers, a total of 112 sealants (56 with laser etching, 56 with acid-etching) were placed onthe permanent premolar and molar teeth. All restorative procedures except application of laser was performed by the same dentist. After completionof the laser- and acid-etching, adhesive was applied, then a pit and fissure sealant, Clinpro Sealant, was placed and polymerized. Clinicalevaluations were done at baseline and 6-, 12- and 18-month recalls by two calibrated examiners, who were unaware of which etching methodhad been used. The retention of sealants and caries were evaluated with the aid of dental explorer and an intra-oral mirror. Each sealant wasevaluated with the following criteria: 1=completely retained; 2= partial loss; 3= total loss. The Pearson Chi-square test was used to evaluatedifferences in the retention rates among the sealants used with different etching methods.Results: All patients attended the 18-month recall and all restorations were evaluated. At 6-month, the retention rate for fissure sealants were 96.4% and 98.2 % for Er, Cr:YSGG laser- and acid-etched teeth, respectively. The retention rates at 12-month were 91 % for laser- and acid-etchedgroups. At the end of 18-month 91 % of the teeth etched with laser and 89.2% of those etched with acid were recorded as "completely retained".There were no statistically significant differences in retention rates among the etching methods after 6, 12 or 18 months (p>0,05). No secondarycaries was detected in association with any sealants.Conclusion: The clinical performance of fissure sealants placed after Er, Cr:YSGG laser or acid-etching were similar.