Perinatal health professionals are in key positions to either promote or dissuade the use of Natural Family Planning (NFP). The purpose of this article is to describe a survey conducted with perinatal physicians and nurses on their knowledge and professional use of NFP. Four hundred and fifty physicians and nurses (150 MDs and 300 RNs) were sent a questionnaire on the use of and knowledge of NFP. One hundred sixty-six (or 37%) returned the completed questionnaires. Fifty-two percent of the nurses who returned the questionnaires and 48% of the physicians indicated they were taught about NFP in basic (generic) medical or nursing school. The average lecture time spent on the subject in either nursing or medical school was less than one hour. The majority learned about NFP through self-education or on-the-job training. Only four (1 RN and 3 MDs) are certified to teach NFP. Fifty-three percent of the nurses and 44% of physicians would not advise the use of NFP to avoid pregnancy. The most frequent reasons given for not promoting the use of NFP to either avoid or achieve pregnancy were that it is not effective, not natural, too difficult to learn, better methods are available, and it only works for highly motivated educated women.