We sought to describe current attitudes and practices of obstetrician-gynecologists regarding use of progesterone and prevention of preterm birth. A self-administered survey was mailed to American College of Obstetricians and Gynecologists Fellows and Junior Fellows in Practice in March to May 2007. The survey consisted of 36 questions, including respondents' demographic characteristics, preterm birth risk factor knowledge and screening practices, and use of progesterone for the prevention of preterm birth. The response rate was 52% ( N = 345); most respondents were general obstetrician-gynecologists (89%). Many (74%) reported recommending or offering progesterone for prevention of preterm birth. Almost all (93%) reported use for the indication of previous spontaneous preterm birth. However, many also reported use for other indications such as dilated/effaced cervix (37%), short cervix on ultrasound (34%), and cerclage (26%). These results suggest that most obstetricians recommend or offer progesterone to prevent preterm birth for women with a previous spontaneous preterm birth and many also offer it for women with other high-risk obstetric conditions.