Purpose: To compare a developmental indirect resin composite with an established, microfilled directly placed resin composite used to restore severely worn teeth. The cause of the tooth wear was a combination of erosion and attrition. Materials and Methods: Over a 3-year period, a total of 32 paired direct or indirect microfilled resin composite restorations were placed on premolars and molars in 16 patients (mean age: 43 years, range: 25 to 62) with severe tooth wear. A further 26 pairs of resin composite were placed in 13 controls (mean age: 39 years, range 28 to 65) without evidence of tooth wear. The material was randomly selected for placement in the left or right sides of the mouth. Results: Sixteen restorations were retained in the tooth wear group (7 indirect and 9 direct), 7 (22%) fractured (4 indirect and 3 direct), and 9 (28%) were completely lost (5 indirect and 4 direct). There was no statistically significant difference in failure rates between the materials in this group. The control group had 21 restorations (80%) that were retained (10 indirect and 12 direct), a significantly lower rate of failure than in the tooth wear patients (P = .027). Conclusion: The results of this short-term study suggest that the use of direct and indirect resin composites for restoring worn posterior teeth is contraindicated. Int J Prosthodont 2006;19:613–617.