With the more sophisticated radioimmunoassay serum hormone testing available, many clinicians bypass the hormonal cytology commonly expressed as the maturation index (MI). A specimen to measure the MI may be collected during a vaginal speculum examination at the same time a Pap smear is taken. Although an MI is typically included on Pap smear results, the significance of the findings is frequently overlooked. The results of accurately collected MI specimens may alert the clinician to ongoing hormonal influence. Although MI specimens may be obtained from various sites, MI readings from vaginal specimens are the emphasis of this article. Description, collection method, interpretation, factors altering readings, key related subjective and objective information, and an update on the current uses of the MI are presented.