Purpose: The aim of this clinical follow-up study was to determine the clinical performance of ormocer and a new nanofill composite material, lined or not lined with flowable composites, after 2 years. Materials and Methods: Occlusal restorations (n = 108) were placed in 54 patients with two symmetric restorations per patient. In one of the two restorations in each patient, cavities were first lined with the flowable composite material Admira Flow or Filtek Flow after applying the two-step total-etch one-bottle adhesive (Admira Bond) or single bond adhesive (Single Bond). Admira or Filtek Supreme was then applied. Restorations were examined using the USPHS modified Ryge criteria for retention, color matching, cavosurface marginal discoloration, anatomic form, marginal adaptation, surface texture, and secondary caries by two previously calibrated dentists. The overall performance of the restorations was evaluated by Wilcoxon signed ranks test. The chi-square test was used to determine differences in the performance of the restorations in which the flowable composite was applied first. Results: There was no secondary caries or postoperative sensitivity in any of the restorations at the 6-month, 1-year, and 2-year follow-up examinations. After 2 years, only one Admira restoration had failed; all other restorations were available for evaluation. There were no statistically significant differences among the materials regardless of the prior use of flowable material (p > 0.05). There was no statistically significant difference between the restorations with and without the prior application of flowable materials (p > 0.05). Conclusion: The clinical performance of occlusal restorations using ormocer or nanofill composite did not benefit from the additional use of the flowable composite. Both of the restorative materials exhibited ideal clinical performance. Keywords: ormocer, nanofill composite, flowable liner, clinical evaluation