This clinical study was undertaken to compare a composite resin, containing a modified filler, with a dental amalgam alloy in Class II restorations. Eight senior dental students placed 98 pairs of restoration in 69 patients. After six months and one-year, 69 pairs of restorations in 49 patients were evaluated by two examiners. No significant differences were found between baseline and one-year evaluations for ratings of anatomic form and marginal adaptation. Color match was found to decrease in time, and marginal discoloration was found to increase in time. Failures of restoration were not attributed to the materials, but more probably were caused by faulty cavity preparations. Although the results for each patient analysis indicated no significant differences in anatomic form and marginal adaptation at one year, the B ratings for these two criteria for both types of restorations in this study indicate the need for continued clinical evaluation. The decreased number of composite restorations with good color match is not unexpected and indicates the need for judgment when selecting composite resin as the restorative material in Class II preparations for esthetic purposes. The significant number of composite restoration in this study with increasing marginal discoloration is reason for concern and continued evaluation of these restorations. Marginal discoloration and poor marginal adaptation are factors related to recurrent caries and replacement of restorations. Thus, continued research and clinical evaluation of new restorative materials is a necessity.