A material investigation is a very important step in the documentation of the component's properties for materials of an object, in estimating its condition, and in considering appropriate conservation treatments. Textile fibers are the fundamental unit of material that makes up fabrics and textiles. Fibers are frequently classed as either natural or man-made, though there are also several categories and sub-types. Natural fibers are further categorized based on their origin (vegetable, animal, or mineral). According to that, this chapter deals with investigation methods for both main components of ancient textiles, fibers, and dyes; as the analysis of the materials utilized in textile dyeing could also be a valuable tool to know how an object originally looked, how old it is, and where it comes from. This data allows conservators to settle on appropriate procedures for restoration and dating textiles depending upon its manufacturing discovery date and its type of dye.