The purpose of this study was to evaluate a nanofilled and a nanohybrid composite, in combination with manufacturer-recommended etch-and-rinse adhesives, in class IV cavities. Thirty-four patients aged 14-46 years (mean age, 27.1 years) comprised the study group. Twenty-six patients received two class IV restorations and eight patients received four class IV restorations. For each patient, half the number of restorations were performed using a nanohybrid composite (Ceram X duo) and the remaining half used a nanofilled resin composite (Filtek Supreme XT), with two-(XP Bond) and three-step (Scotchbond Multipurpose) etch-and-rinse adhesives, respectively. Two experienced examiners evaluated the restorations for retention, color match, marginal discoloration, wear/loss of anatomic form, caries formation, marginal adaptation, and surface texture to compare the baseline (after placement) and annual recalls over 5 years. The cumulative success rates for the Filtek Supreme XT and Ceram X duo restorations after five years were 86.2% and 89.7%, respectively. Four Filtek Supreme XT and three Ceram X duo restorations failed. There was no statistically significant difference between the nanofilled and nanohybrid composites at any of the evaluation periods for any of the parameters evaluated. Despite the limited number of restorations, all restorations were clinically acceptable regarding retention, color match, marginal discoloration, wear or loss of anatomic form, the formation of caries, marginal adaptation, and surface texture, except the failed restorations. Fracture was the main cause of restoration failure.