Abstract Background: Skull defects may occur following trauma, infection, tumor invasion and neurosurgical procedures like decompressive craniectomy. Large defects should be recon-structed for brain protection and normalization of cerebral hemodynamics. Aim of Study: To evaluate the use of prefabricated cus-tomized 3D printed implants for cranioplasty of skull defects >4cm in diameter. Patients and Methods: The study included 20 patients with skull defects >4cm in diameter operated upon by crani-oplasty using prefabricated 3D printed PEEK implants in the period from March 2017 to April 2018. Patients were assessed for cosmetic results, cost, operative time and complications. Pre and post-operative CT scans with 3D reconstruction were performed in all patients. Patients were followed-up clinically and radiologically for 6 months following surgery. Results: The study included 15 males and 5 females with an average age of 39.4 years. The cause of skull defect was trauma in 9, tumor invasion in 7, decompressive hemicraniec-tomy in 2 and infection in 2 patients. The average defect size was 7.6cm in diameter. Good cosmetic results were achieved in all patients. No complications were encountered except for superficial wound infection in 1 patient and small extradural hematoma in another patient. Conclusion: Use of 3D printed implants for cranioplasty provides excellent cosmetic results with less operative time, blood loss and complications when compared to conventional methods but at a higher cost.