This study was conducted retrospectively to evaluate the clinical performance of preventive resin restorations. Five hundred thirty-two restorations in 351 patients had been in the mouth for a mean of 16.5 %/- 7.6 months. The clinical performance was determined with a modified version of the US Public Health Service rating system. In 79.9% of the restorations, the marginal discoloration was rated as Alfa (no discoloration), while only 0.9% were scored as Charlie (discoloration penetrating in a pulpal direction). The marginal adaptation was rated as Oscar (fully sealed) in 28.4% of restorations; in only 0.4% of restorations, rated as Charlie or Delta, was the dentin or base exposed. In 98.3% of the restorations evaluated, the anatomic form was rated as Alfa (continuous with existing anatomic form). Recurrent caries was associated with 2.3% of the restorations. Chi-squared tests failed to reveal any statistically significant relationships between the clinical performance of the restorations and the length of time in the mouth.