Carcinoma in situ is a frequent finding in pregnancy when cytologic methods are applied as a routine screening procedure. Such testing has been done without risk and has been applied at all stages. Cancer found when unsuspected and in a preclinical state rarely demands radical treatment. Modern management of early lesions which are preinvasive calls for conservative measures and cytologic follow-up, in contrast to clinical cancer, which demands immediate and often radical therapy. The recommended method for adequate biopsy is the cold-knife cone or "ring-biopsy" with the Ayre-Scott conization knife with disposable blade. Infiltration with 100 to 300 ml. of a saline-epinephrine solution makes it possible to excise the surgical specimen without loss of blood. Performed preferably after the third month of pregnancy, the conization procedure is safe.