Perimenopause often represents a physiologically challenging phase in women's lives. The clinical presentation of the perimenopause includes infertility, irregular menstrual cycles, menorrhagia, and new onset of or worsening of mood disorders. Unlike menopause, which is characterized by low levels of estradiol and progesterone, the hallmark of perimenopause is highly variable levels of estradiol and progesterone with abrupt increases and decreases that are often described as a hormonal roller coaster. This chapter invites general gynecologists to understand the hormonal basis of the common complaints of perimenopause and offers information about the physiology of these issues and helpful treatment options.