The Masquelet procedure or induced membrane technique presents a treatment option for relatively large osseous defects, e.g. after trauma, tumour resection or osteomyelitis even in the presence of unfavourable soft tissues. Initially developed at the end of the last century by the French surgeon Masquelet, the technique relies on a bioactive membrane that forms a foreign body reaction around a cement spacer. This spacer is implanted in the residual defect after rigorous debridement of bone and soft tissue during a first-stage procedure. A second-stage intervention is performed 1-2 months later with removal of the spacer under preservation of the membrane that has since formed around the cement. The membrane acts as an internal bioreactor exerting its effect via a rich vascularization and secretion of growth and differentiation factors. The void within the membrane is filled with an autologous cancellous graft. After adequate stabilisation using standard techniques, a gradual corticalisation of the graft can be observed over the duration of several months, with remodelling in the long-term course.The following article describes the original technique, our preferred approach including indication, surgical technique and postoperative follow-up. Additionally, the biological background and clinical tips and tricks are presented.