To evaluate the 3-year clinical performance of the compomer Hytac in Class I and II cavities of permanent posterior teeth.53 restorations were placed in 14 patients. The compomer Hytac was used with the self-etching adhesive Hytac OSB (total bonding) without additional enamel-etching with phosphoric acid according to manufacturer's instructions. Restorations were rated at baseline and 3 years according to modified USPHS criteria in relation to tooth type (molar, premolar), size and class of cavities, isolation type (rubber dam, cotton rolls) and use of a calcium hydroxide liner. After 3 years, 39 restorations (73.6%) were available for examination. Statistical analysis was performed using Mann-Whitney U test and Fisher's exact test.After 3 years, three restorations failed (7.7%). The success rate was therefore 92.3% with an average annual failure rate of 2.6%. There was no statistically significant difference (P < 0.05) found concerning neither of the USPHS criteria nor the failures between any of the restoration groups.