Large tumours of the mandible need immediate reconstruction to provide continuity of the mandible, satisfactory function of the jaw, as well as an acceptable aesthetic outcome. In this prospective study we described the immediate reconstruction of the mandible using computer aided design and 15 rapid prototyped patient specific implants (PSI) in 14 patients suffering from benign or malignant tumours demanding continuity resection of the mandible. The scaffold PSI was filled with beta-tricalcium phosphate granules and autologous bone. Microvascular reconstruction was additionally needed in 12/15 cases. The clinical follow up was on average 33 months and the radiological follow up was on average 21 months. In nine cases the healing was uneventful. One patient lost the microvascular flap during the first postoperative week and one patient needed a revision due to perforation of the mucosa at the site of the PSI. Four patients had a major complication due to perforation of the mucosa leading to infection, which resulted in the total or partial removal of the PSI. The PSI seems to be a promising solution for treatment of patients demanding large reconstruction after mandible resection. The benefits are decreased rate of donor site complications and more accurate and prompt surgical procedure. (C) 2016 Published by Elsevier Ltd on behalf of European Association for Cranio-Maxillo-Facial Surgery.