Patterned hair loss is the most common type of hair loss affecting men and women belonging to all age groups; hence, this chapter is focused on Male Pattern Hair Loss (MPHL) and Female Pattern Hair Loss (FPHL). The management of patterned hair loss has a great bearing on the anatomy and physiology of the hair follicle and scalp; hence, its importance cannot be understated. Knowing the structure and composition of a follicular unit assists in choosing the right punch in order to minimize transection. The understanding of the hair cycle forms the basis of Body Hair Transplant (BHT).