Purpose: The aim of this study was to evaluate plaque accumulation and peri-implant tissue response adjacent to machined and dual acid-etched (DAE) titanium implant surfaces. Materials and Methods: Two types of implants were used-control implants with a DAE surface in their apical portion and a machined coronal part, and test implants with a DAE surface throughout their entire length. A total of 10 sets of implants were placed in the posterior quadrants of eight patients, with at least 2 implants (1 control and 1 test implant) placed in each site. Machined healing abutments were placed on the control implants and DAE-surfaced healing abutments on the test implants. Plaque Index and bleeding on probing (BOP) were recorded together with histologic and microbiologic analyses of the peri-implant tissues. The healing abutments underwent a scanning electron microscope scan at 5 months postsurgery. Standardized radiographs were also taken at the time of implant placement and 3, 6, and 12 months postsurgery. Results: DAE surfaces accumulated more plaque than machined surfaces (P .0006) and the plaque was assessed as more difficult to remove (P .0143). No histologic abnormalities were seen and the test implants showed significantly lower crestal bone resorption than the control (P .0174). Conclusion: DAE healing abutments showed an increased plaque accumulation, but no significant BOP differences or histologic analyses were found between test and control sites. The test implants showed less interproximal bone resorption than the control ones at the end of a 1-year follow-up evaluation.