Intimate apparel is the most important clothing layer since it acts as human's second skin due to contact with the skin directly. The comfort issues for intimate apparels are sensorial, thermal, motion, and aesthetical, all of which are interrelated. Since intimate apparel is an inner layer in between the skin and the outerwear, its thermal comfort is very important. Transferring moisture from the clothing to the environment through diffusion, wicking, sorption, and evaporation is regulated by the thickness and tightness of the fabric. On the other part, the behavior of fabric is affected by chemical and physical properties of its constituent fibers, fiber content, physical and mechanical characteristics of its constituent yarns, and the finishing treatments. Thus, major fiber manufacturers such as Nylstar, Invista, and Lenzing have launched different types of fibers such as Meryl Skinlife, Tactel, Tencel, etc., which are suitable for intimate apparel. The aim of this chapter is to introduce the latest developments in fibers used in the manufacturing of intimate apparel products and their contribution to clothing comfort, which the apparels give when the body does not limit its movement and regulation mechanism of its own temperature.