This chapter discusses the prevalence of infertility and the importance of the initial assessment of the infertile couple. Education of the public about the known decline in fertility that occurs with age, particularly in women older than 35 years, is important. The preliminary investigation centres on the need to demonstrate that the woman is ovulating. Semen analysis remains the most important means of assessment for male. In the fertility clinic setting, a pelvic ultrasound examination may be useful. Diagnostic categories in most studies include male factors, disorders of ovulation, tubal factors, endometriosis and uterine factors related to infertility, and unexplained infertility. Ovulatory disorders, often associated with irregular menstruation, are associated with reduced chances of natural conception. Ovulation induction provides good chances of success if there are no other complicating factors such as tubal compromise or severe impairment in sperm quality.