Relating emergency contraception, commonly referred to as "the morning-after pill," to the menstrual cycle can be used both to teach endocrine function and to show how physiology relates to the world outside the undergraduate classroom. The menstrual cycle is an excellent topic for teaching many features of the physiology of the human endocrine system. Relating emergency contraception to the menstrual cycle makes this topic relevant to both male and female students, provides opportunities for discussions that require the students' understanding of endocrine functions, and illustrates how physiology is connected to social, economic, and political issues. The overview of emergency contraception and literature survey provided here are meant to be adapted for use in a variety of teaching contexts. The depth of coverage and the extent of consideration of issues beyond physiology would depend on many factors including the level of the course and the size of enrollment.