The diagnostic imaging (DI) literature identifies that unnecessary examinations are occurring. However, there is a gap in the research literature: little is known about how physicians order DI examinations and what efforts need to be undertaken to reduce the number of inappropriate orders made by physicians. Such research is needed in order to promote patient safety and improve utilization of limited health care resources Purpose: The purpose of this study is to explore how physicians order DI services, and what efforts could be made to reduce inappropriate DI ordering. Participants: 12 English speaking, non-radiologist physicians (general practitioners and specialists) participated in this study. Methods: Semi-structured key informant interviews were conducted with participants. Data from these interviews were analyzed using a grounded theory approach. Results: DI ordering practices (both appropriate and inappropriate) emerged as the dominant theme in this research, specifically in the context of prevalence, decision-making, information support, contributing factors, and solutions. Particularly, the majority of participants felt that DI is overused in the medical field and identified contacting physicians (colleagues, specialists, or radiologists) and consulting the literature (using UpToDate® or Google Scholar) as their top methods of information support used in challenging clinical scenarios. Meanwhile, participants suggested factors that contribute to inappropriate ordering: patient demand, legal liability, and duplicate ordering. The majority of participants believed education could reduce inappropriate ordering. Participants also identified increasing communication about requisitions and restricting DI ordering authority as potential solutions to reduce inappropriate ordering. Conclusion: From the interviews, ordering (both appropriate and inappropriate ordering) emerged as the overarching theme. Findings were compared and contrasted to the current literature. Overall, this study revealed how human factors, such as patient demand, influence how a physician orders DI. As well, the majority of participants relied on the patient to recall patient DI history; however, literature suggests this method is unreliable. This study also offers unique insight into the physician’s perspective of what would be effective for reducing inappropriate ordering. These findings contribute to the field of health informatics as any technology developed to reduce inappropriate ordering (such as a clinical decision support system) needs to consider these human factors to support user acceptance. Through findings from this study, further research gaps emerged that can guide future research. / Graduate