Silk fibers are a renewable protein biopolymer, which has the excellent mechanical properties and is also biocompatible. It is not only widely used in the textile industry but is also commonly used in medical applications. As silk fibers possess good biocompatibility and bioresorbability properties they were used in ancient times for biomedical engineering and surgical applications. Using silk fiber as a reinforcement for biopolymers could enhance the stiffness of scaffoldings and bone implants. Being a part of the fibrous protein family, silk possesses great mechanical strength, which in turn makes it suitable for use as a biomaterial. The evolution of silkworm silk started with its biomedical application as sutures for wound treatment. As silk fiber possesses excellent characteristics such as biocompatibility, absent or minimal immunogenicity, limited bacterial adhesion and controllable biodegradability, this natural biopolymer has been found to be appropriate for a variety of biomedical engineering applications. Raw silk fiber consists of silk fibroin, which is coated with a protein glue called sericin. Degumming is a surface modification process for the removal of sericin, which allows for wide control of the silk fiber’s properties, making the silk fiber suitable for use in the development and production of novel biocomposites with required mechanical and biodegradable properties. In the absence of sericin, that is, silk after the process of degumming, it can be employed in implantation and cell culture, as it prevents or allows only minimal inflammation. After the degumming process, silk fibers can be directly structured into three-dimensional frameworks called scaffolds. Following the consideration of the material properties and different architectures for fabrication, this chapter also deals with the biomedical and bioengineering applications of silk. © 2019 Elsevier Inc. All rights reserved.