Objective: Duraplasty with a dura mater substitute can become necessary after cranial or spinal surgery. Several dura grafts from different materials are available. The goal of this study was to assess the clinical performance of a suturable onlay dura substitute composed of bovine collagen. Methods: A prospective, observational, multicenter, single-arm clinical study with the dura substitute Lyoplant® Onlay was performed. Different performance parameters for safety and performance were assessed. Additionally, postoperative MRI / CT images were evaluated. Results: Data of 61 patients recruited by three study centers were included. Lyoplant® Onlay was used by a variety of surgeons with different levels of experience. Cranial and spinal cases with a wide range of dura defect sizes were included. No reoperation due to a cerebrospinal fluid leakage occurred until discharge (primary endpoint), as well as to the follow-up (about four months postoperatively). The incidence rate of cerebrospinal fluid leakages was 6.6%. All of these adverse events were reported as non-serious complications without the need of a surgical intervention and were resolved without sequelae. The handling properties of Lyoplant® Onlay were positively rated. In external radiologic analysis of postoperative MRI / CT images at discharge and follow-up, additional fluid collection, edema, and swelling were observed. However, they were clinically inapparent and considered normal postsurgical findings. Conclusions: The incidence rate of cerebrospinal fluid leakages was 6.6% and ranged in the values reported in the literature. These results show that Lyoplant® Onlay is a safe and efficient dura substitute.