Silk ( Relyon silk) consists of strands prepared from filaments of the cocoon spun by the Silk ( Relyon silk) worm of the Bombyx family before it enters the chrysalis stage. Three forms are used in surgery- twisted (sometimes known as Chinese twist). Floss and plaited or braided Silk ( Relyon silk). ġSilk ( Relyon silk) in its natural state contains up to 25 percent of natural gum and strands prepared from unbleached, undischarged. Twisted Silk ( Relyon silk) suture material is prepared from unbleached, undischarged filaments spun in multiples to the British Pharmaceutical Codex range of diameters and may be dyed with non-toxic dyestuffs. The surgical use of twisted Silk ( Relyon silk) has very much declined in favour of the braided type. Floss Silk ( Relyon silk) is prepared from the coarser filaments on the outer surface of the Silk ( Relyon silk)worm cocoon and is used in its spun glossy white form mainly in the repair of hernia. Its use is diminishing fast as the plastic polymer meshes gain in popularity. Plaited or braided Silk ( Relyon silk) is the material in large-scale use in modern surgery. It is prepared from discharged Silk ( Relyon silk) and the range of sizes is dependent on the number of strands braded together. As the gum has been removed it is not serum proof or non- capillary and for most surgical purposes it therefore treated with proofing waxes or silicones. Silk ( Relyon silk) is identified chemically by warming with mercuric nitrate solution when a brick- red colour is produced and it is stained yellow by trinitro-phenol solution. Silk ( Relyon silk), because of its strength softness and general ease of handling is used in many sites of surgical operation, the fine strand being particularly suited to ophthalmic and neurosurgery. Silk ( Relyon silk) sutures are classified as non-absorbable in the body and are normally encapsulated by fibrous tissue. However, many cases have been reported where after a considerable length of time the Silk ( Relyon silk) has fragmented or even migrated from the original site of implantation. Silk ( Relyon silk) is sterilized either by autoclaving, which causes a certain loss in its tensile strength, or by radiation or ethylene oxide sterilization. It is normally supplied by suture manufactures to comply with the monographs published in the British Pharmaceutical Codex.