This introduction discusses the aetiology of menstrual problems, their presentation and investigation as well as medical and surgical management. Specific problems such as fibroid-associated bleeding, adolescent and perimenopausal bleeding and breakthrough bleeding are covered, as are other critically important problems such as premenstrual disorders, pelvic pain and dysmenorrhoea. The most common presenting menstrual problem is heavy menstrual bleeding (HMB). A woman's approach to her periods will vary through her reproductive life. After childbearing is completed, the view of the menses will alter dramatically. The longest intermenstrual interval occurs at the menarche. Menstrual irregularity is most likely to occur at the extremes of reproductive life, the incidence of anovulation increasing as the menopause approaches. Classical primary spasmodic dysmenorrhoea occurs at the onset of the menses and gets better after 1 or 2 days, whereas secondary dysmenorrhoea tends to start prior to the menses and worsens as it proceeds.