PIP: This analysis covers 156 case histories of women fitted with cervical caps in an attempt to encourage further research on a larger patient group. The contraceptive prescribed for almost all women was a plastic cervical cap imported from abroad. Observations with a new American made plastic cap were begun a short time ago and will be published in the near future. After the absence of any cervical pathology was ascertained during routine gynecological examination, the size of the cervical cap was determined by rough estimation as "large," "medium," or "small." The cervical cap is cleansed with water and soap, dried, and lubricated with jelly and then the cap is filled with spermicidal cream or jelly. The woman is placed in the lithotomy position, 2 fingers of the left hand separate the labia. The cervical cap is held between index and middle fingers of the right hand and inserted into the vagina, following the posterior wall to the posterior fornix. Here the cap is released and will slip almost automatically over the cervix. For self insertion the woman is taught to feel her own cervix, and then she is directed to follow this same technique. For removal of the cap, index and middle finger are inserted into the vagina, reaching high up in the fornix. As the rim of the cap is reached it is tilted away from the cervix. Thereafter the cap is grasped between the 2 fingers and removed. The objection most often raised against the cervical cap is that the technique is too difficult for the women to learn, but Marie Stope and Hannah Stone experienced no difficulty in teaching thousands of women the technique. Only 13 of the 156 women encountered difficulties in learning self insertion. The most frequent side effect of the use of the cap was discharge, especially in cases where it was left in for the 24 days between 2 menstruations. In no case did the discharge amount to a major disturbance. The plastic cap has less tendency to induce discharge than other firm caps. Increased discharge in the presence of an erosion was observed in 9 cases. Acute and subacute pelvic inflammatory disease are an absolute contraindication for the cervical cap. There is no large group of statistics which attest one way or the other as to the reliability of this method. Histories are cited to demonstrate the effectiveness and harmlessness of the cervical cap as a contraceptive method. Of 90 observations of the cervical cap in the clinic group, 49 were chosen to evaluate the reliability factor. There were 7 pregnancies in this group. Of 40 women seen in private practice, 7 experienced unwanted pregnancies.