Purpose: Polyether-ether-ketone (PEEK) implants have become increasingly popular for use in reconstructive procedures. It is imperative to understand the consequences of using this biomaterial in anatomic sites that can pose a risk of infection. Specifically, the use of PEEK in paranasal sinus cavity reconstruction is not well documented. This study examined postoperative complications, namely surgical site infection and implant loss, in patients who underwent paranasal sinus cavity reconstruction using PEEK implants. Materials and Methods: This study is a single-center case series. Patients who underwent craniomaxillofacial reconstruction with a custom-made PEEK implant in intimate contact with a functional paranasal sinus from June 2013 to May 2017 were included. Baseline characteristics and preoperative and postoperative variables were collected by retrospective chart review. Results: Eight patients were included in this study. Average patient age was 45.75 ± 19.36 years. Average follow-up duration was 300 ± 263 days. Mean operative time for PEEK implantation was 214.13 ± 66.03 minutes. Implant size ranged from 5 to nearly 100 cm2. No patients were diagnosed with acute or chronic sinusitis postoperatively. One patient underwent explantation of his PEEK implant secondary to breakdown of overlying skin that separated from the site of the frontal sinus because of coagulase-negative Staphylococcus epidermis infection. Conclusions: Literature review indicates that this is the largest case series reported to date documenting the use of PEEK implants in reconstruction of the region of the paranasal sinuses. Specific biologic, or alloplastic, barriers outside the formation of native scar tissue or regional fasciocutaneous tissues at the sites of reconstruction were not used in these reconstructions, although consideration for placement of these barriers can be at the discretion of the operative surgeon. The authors conclude that PEEK implants can be used in complex craniomaxillofacial reconstructive procedures to achieve near anatomic reconstruction not easily attainable through conventional means. Defects that involve the paranasal sinus cavities with a functional ostium or obliterated sinus cavity can be reconstructed with PEEK implants without increasing the risk of infection and need for explantation. Long-term follow-up and continued outcome results of this treatment modality will be necessary to verify its clinical usefulness in the future.