en Neurotrauma Case Series <strong>Background and Importance:</strong> Patient-specific polyetheretherketone (PEEK) implants are increasingly used in cranioplasty due to their biocompatibility, radiolucency, and favorable cosmetic outcomes. However, postoperative complications such as fluid collections remain a clinical concern.<br> <strong>Case Presentation:</strong> We describe two male patients with severe traumatic brain injury who underwent bilateral decompressive craniectomy followed by delayed cranioplasty using custom-made PEEK implants. Both patients developed recurrent epidural and subgaleal effusions during follow-up. The first case was successfully managed conservatively with aspiration, corticosteroid therapy, and compressive bandaging. The second case developed progressive effusion resistant to conservative management, ultimately requiring implant removal and reconstruction with a titanium mesh, which resolved the complication. Although PEEK implants offer significant advantages in cranial reconstruction, they may be associated with recurrent effusion. Conservative management may be sufficient in some cases; however, persistent or refractory effusions may necessitate implant removal. Careful follow-up is essential for early detection and management of such complications.<br> <strong>Conclusion:</strong> Although PEEK implants offer significant advantages in cranial reconstruction, they may be associated with recurrent effusion. Conservative management may be sufficient in some cases; however, persistent or refractory effusions may necessitate implant removal. Careful followup is essential for early detection and management of such complications. Cranioplasty, Polyetheretherketone (PEEK), Epidural effusion, Subgaleal effusion, Decompressive craniectomy, Titanium mesh 0 0 http://irjns.org/browse.php?a_code=A-10-632-2&slc_lang=en&sid=1 Morteza Modaenama Morteza_Moddaeinama@gums.ac.ir 100319475328460012603 100319475328460012603 Yes Guilan Road Trauma Research Center,Trauma Institute, Guilan University of Medical Sciences, Rasht, Iran. Khatere Mokhtari khatere_mokhtari@yahoo.com 100319475328460012604 0009-0002-1179-4769 No Department of Cell and Molecular Biology and Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran.