Introduction: In recent years a new perforated PDS (poly-p-dioxanon) foil (0.15 mm) has become available and has not yet been proven to be successful in reconstruction of the orbital floor after blow-out-fractures in randomized studies. The main aim of this clinical trial is to compare this new PDS foil with titanium dynamic mesh (0.3 mm) (TD), which is well established in reconstruction of the orbital floor. Patients and Methods: In a prospective multicentre randomized trial, conducted between 1997 and 1998, out of 42 patients with fractures of the orbital floor, 28 patients needing material for reconstruction were randomized to receive either PDS foil or TD. In a comprehensive preoperative and postoperative protocol patients were monitored by the surgeon, radiologist and ophthalmologist with a postoperative follow-up of least 6 months. Results: Maximum defects of the orbital floor were comparable in both groups (PDS group: 13.3 mm, TD group: 13.9 mm). In both groups the surgical procedure was well tolerated, and functional and cosmetic results were evaluated as satisfactory by all patients. Ophthalmological evaluation, performed up to 6 months postoperatively, revealed double vision or vertical strabismus in nine patients (five PDS group, four titanium group). This was not confirmed subjectively in each single patient. Also ex- or enophthalmos, registered in seven patients of the PDS and four of the TD group (mainly +/-1 mm) were not considered as relevant by the patients. Conclusion: The new 0.15 mm perforated PDS foil was comparable to 0.3 mm titanium mesh concerning functional and cosmetic outcome. Obviously, persisting ophthalmometric disorders were compensated very well in both groups. PDS foil is felt to be the preferred material since it is bioresorbable and more convenient to handle. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.