Purpose: The aim of this study was to characterize and compare the behavior of human osteoblasts and human gingival fibroblasts in contact with polyetheretherketone (PEEK), zirconia, and titanium implant surface materials. Materials and Methods: PEEK, yttria-stabilized zirconia (YTZP), and titanium disks were produced under appropriate and similar conditions to achieve controlled surface features. Human osteoblasts and human gingival fibroblasts were cultured on disks for 14 days. Cell viability and proliferation were evaluated using a resazurin-based method. Morphology and cellular adhesion were observed using field emission gun-scanning electron microscopy (FEG-SEM). Alkaline phosphatase (ALP) activity and bone cell mineralization was evaluated on osteoblasts. Confocal laser scanning microscopy (CLSM) images of fluorescent-stained fibroblasts were obtained at 7 and 14 days of the culture. Results were presented as mean and standard deviation (SD). Group comparisons were tested using analysis of variance (ANOVA) (Tukey's post hoc) with appropriate statistical software, and significance was set at P .05. Results: Cell viability and proliferation were higher in PEEK and YTZP groups compared with titanium on osteoblast cells (P .05, all time points) and on fibroblasts (P .05, 7 and 14 days). All groups showed an increase in ALP activity over time, which was not significant. Mineralization patterns demonstrated an increase in mineral content over time, which was more apparent in the YTZP group. Cell spreading was more evident on PEEK and YTZP specimens. Conclusion: The results suggest increased adhesion, viability, and proliferation of osteoblasts and gingival fibroblasts on zirconia and PEEK surfaces compared with titanium. These results are correlated with the increased wettability of these materials. Keywords: dental implants, fibroblasts, osteoblasts, polyetheretherketone, titanium, zirconium oxide