The practicing emergency physician often encounters diagnostic dilemmas involving the choice of the most appropriate radiologic study to evaluate patients in the emergency department. In addition, the uncertainty of potentially harmful fetal effects of radiation in the pregnant patient may add unnecessary delay and concern in the workup of obstetric emergencies. An emergency physician's in-depth understanding of the strengths, limitations, and potentially harmful effects of radiologic studies allows the safest and most appropriate studies to be ordered for the gynecologic and obstetric population. With the explosion of interest and growing level of expertise in focused emergency department ultrasonography during the last decade, the practicing emergency physician should add this skill to his or her armamentarium in the future. Many emergency physicians are already comfortable in using radiologic technologies in their daily practice and have discovered how quickly vital and specific information can be obtained.