Embryology is the study of formation and development of embryo from the moment it is formed to the time when it is born. This chapter covers the mitosis and meiosis, spermatogenesis and oogenesis, menstrual cycle and changes in uterus, ovulation and tests for ovulation, fertilization, implantation, germ layer formation, placenta, and sex determination. Multiplication of cells takes place by division of pre-existing cells. This is an essential feature of formation of embryo. There are two types of cell divisions following as mitosis and meiosis. Fertilization is the process whereby the sperm and the ovum fuse to form a zygote. After the release of ovum from the ovary, it is picked up from the peritoneal cavity by the fimbriae of the fallopian tube. In this chapter, short essay type questions are also provided.