A critical part of interpreting radiologic images is determining the need for potential follow-up imaging. Reported rates of follow-up recommendations in radiology reports range 8%-37% (1-6) with high rates of interobserver variability (7). Even radiology reports with noncritical findings may contain recommendations for further imaging by using different modalities or recommendations for interval followup by using the same modality (5). Furthermore, there are known differences in radiologists' familiarity and adherence with evidence-based guidelines (8-10). This may lead to unnecessary additional tests in the follow-up of incidental or ambiguous imaging findings (11,12). A better understanding of follow-up recommendations in radiology reports is needed, as are clear identification of factors that might account for variation in rates of follow-up recommendations. Previous studies (5,13) performed at single institutions and in single subspecialty divisions have suggested that radiologist experience may be associated with fewer follow-up recommendations. However, it remains poorly understood how much radiologists vary when recommending additional imaging and what additional radiologists and other factors influence the likelihood of additional imaging. We hypothesized there is a large amount of likely unwarranted variation among radiologists in terms of the probability of making a follow-up recommendation. Therefore, we sought to identify factors associated with follow-up recommendations in radiology reports from multiple modalities, patient care settings, and imaging divisions to better evaluate features associated with a higher number of follow-up recommendations.