Free tissue transfer has been the gold standard of extensive skull base reconstruction, but the onlay of free flaps onto skull base defects carries the risk of cerebrospinal fluid (CSF) leakage. The purpose of this study was the evaluation of a novel technique of a combined sub- and onlay concept with a partially intracranially positioned folded free fasciocutaneous flap in terms of flap applicability, versatility and complication rate. Within 5 years, 7 patients with anterior (n=4), middle (n=2) or posterior (n=1) skull base defects were reconstructed with free extended lateral arm (n=3) or anterolateral thigh (n=4) flaps. The flaps were partially intracranially positioned and fixed with osteo-dermal sutures. Both flaps proved to be applicable in terms of sealing efficiency, minimizing intracranial flap volume and folding. No flap loss was observed. Specific complications consisted of one pneumocranium via an accessory frontal sinus and one cerebellar herniation due to lumbar CSF loss. No flap failure or haematoma of the intracranial flap part occurred. This new concept of intracranial positioning of fasciocutaneous flaps in a sandwich technique using osteo-dermal sutures should be considered as a primary treatment for skull base reconstruction rather than merely as a salvage manoeuvre.