The wear of five posterior composites at occlusal contact areas (OCA) and contact free occlusal areas (CFOA) was evaluated in Class II cavities over a 3-year period with an accurate 3D-measuring technique. A clinical evaluation was also performed. The ultrafine compact-filled composites (Willems et al., 1992) showed acceptable OCA-wear rates ranging from 110 to 149 microns after 3 years. This is very similar to the OCA-wear rate of human enamel on molars, which is about 122 microns after 3 years. The fine compact-filled composite had an unacceptable OCA-wear value of 242 microns after 3 years. The ultrafine midway-filled composite showed an exceptionally high CFOA-wear value of 151 microns after 3 years, which gave the impression of it being gradually washed out of the cavity. Clinically, 70% of the restorations made with the ultrafine midway-filled composite showed excellent colour match after 3 years. For most of the compact-filled composites slightly opaque fillings were noted and 63% of the restorations made with one of these materials were clearly opaque. It can be concluded that the investigated ultrafine compact-filled composites can be considered as amalgam alternatives as far as their wear resistance is concerned.