Since its introduction as a screen for cervical cancer in the late 1940s, the Pap smear has become one of the most widely accepted screening procedures for cancer. Numerous scientific studies have now attested to its effectiveness. However, important issues related to the Pap smear, including cytologic nomenclature, accuracy, regulatory procedures, and screening guidelines, are still being evaluated and debated. This article provides an overview of important issues related to the Pap smear.