Cranioplasty is not only performed for cosmetic reasons but also for physiological requirements to balance the cerebral hemodynamics and to protect the brain from external traumas. Methyl methacrylate is one of the most preferred materials for cranioplasty. It is usually prepared out of the surgical site and therefore modelling of the cranioplasty material is sometimes difficult to fit the bone defect. In this technical note, we present our new technique of cranioplasty with methyl methacrylate in which the material is prepared on site of the bone defect and very easily shaped. Fixation materials are not needed. This technique is especially suitable for posterior fossa surgeries after craniectomy