Objective: Since an increasing number of composite restorations in posterior teeth are placed as a routine, this study was conducted to evaluate long-term survival of these restorations placed in general practice. Methods: Patients from a private dental office that received restorations in posterior teeth between 1987 and 1988 with P-50 (3M) or Herculite XR (Kerr) resin composites were selected and invited to participate. Restorations were placed under rubber dam isolation. Dentine walls were covered with glass ionomer cement, and composites were placed according to manufacturer's instructions. Thirty-eight patients agreed to participate and signed an informed consent prior to the evaluation. Two calibrated operators worked independently in the evaluation, using modified USPHS criteria. Survival of restorations or subsets of restorations grouped on the basis of variables (material, tooth, cavity type and size) was determined using Kaplan-Meier survival curves. Results: Ninety-eight failures were recorded among the 282 restorations providing a crude estimate of 34.8% failures. The survival rate was not significant for material (p = 0.92) but was significant between tooth bower premolars and lower molars, p < 0.0001), cavity type (p < 0.001) and size (p < 0.001). The majority of restorations exhibited A or B scores for the evaluated criteria. The main failure cause was fracture of both composites. Conclusions: The clinical performance of posterior resin composite restorations evaluated was acceptable after 17-year evaluation. However, the probability of failure of resin composite restorations in molars, Class II, and large restorations is higher. (c) 2005 Elsevier Ltd. All rights reserved.347427435