Objectives: The aim of this study was to investigate the clinical performance of 120 posterior composite restorations placed in 38 patients after a period of 7 years. Method and materials: Eighty-eight Class I and 32 Class II restorations were made (93 molars and 27 premolars) using three different resin composite materials: Z100, Clearfil Ray-Posterior, and Prisma TPH. The restorations were evaluated using Ryge's criteria for color match, marginal discoloration, marginal adaptation, secondary caries, surface texture, and anatomic form at baseline, 1, 2, 5, and 7 years. Photographs and radiographs were taken at each recall period. Results: At 7-year recalls, 70 restorations were available for examination. Four restorations had failed due to secondary caries. Saliva sampling was performed to determine the level of mutans streptococci and lactobacilli for the four failed restorations at the last recall. No statistically significant differences were found among the materials in regard to color match, anatomic form, and secondary caries. Clearfil Ray-Posterior had statistically significantly rougher surface texture than the surrounding enamel compared to the other resin composites. Z100 showed more cavosurface margin discoloration after 5 years than the other two resin composites. All materials had slight marginal adaptation problems at the 7-year recall. There was no apparent relationship between the levels of mutans streptococci and lactobacilli in saliva and the failed restorations. Conclusion: The three posterior composites tested had acceptable clinical performance after 7 years.