Silks have been proposed as potential scaffold materials for tissue engineering, mainly because of their physical properties. They are stable at physiological temperatures, flexible and resist tensile and compressive forces. Bombyx mori (silkworm) cocoon silk has been used as a suture material for over a century, and has proved to be biocompatible once the immunogenic sericin coating is removed. Spider silks have a similar structure to silkworm silk but do not have a sericin coating. This paper provides a general overview on the use of silk protein in biomaterials, with a focus on skeletal tissue engineering.