Two hundred twenty permanent young molars in 60 children aged 8 to 13 years received only one application of a light-activated resinous sealant. The retention rate was assessed 6 and 12 months later. The teeth were divided into 2 groups of 110 each. In one of the groups the pits and fissures were etched with 37% phosphoric acid before being sealed (group 1); in the other (group 2) these areas were etched with 10% maleic acid. The retention rate of group 1 was 98.4% at 6 months, and 96.8% at 12 months. Group 2 had retention rates of 97.5% at 6 months and 95% at 12 months. There was no statistically significant differenc e between the two groups in the two test periods, nor were there differences in the same group at the different periods.