Objectives: Computed tomography (CT) use has increased dramatically over the past 2 decades, leading to increased radiation exposure at the population level. We assessed trends in CT use in a primary care (PC) population from 2000 to 2010. Methods: Trends in CT use from 2000 to 2010 were assessed in an integrated, multi-specialty group practice. Administrative data were used to identify patients associated with a specific primary care provider and all CT imaging procedures. Utilization rates per 1000 patients and CT rates by type and medical specialty were calculated. RESULTS: Of 179,032 PC patients, 55,683 (31%) underwent CT. Mean age (SD) was 31.0 (23.6) years; 53% were female patients. In 2000, 178.5 CT scans per 1000 PC patients were performed, increasing to 195.9 in 2010 (10% absolute increase, P = 0.01). Although utilization rates across the 10-year period remained stable, emergency department (ED) CT examinations rose from 41.1 per 1000 in 2000 to 74.4 per 1000 in 2010 (81% absolute increase, P < 0.01). CT abdomen accounted for more than 50% of all CTs performed, followed by CT other (19%; included scans of the spine, extremities, neck and sinuses), CT chest (16%), and CT head (14%). Top diagnostic CT categories among those undergoing CT were abdominal pain, lower respiratory disease, and headache. Conclusions: Although utilization rates across the 10-year period remained stable, CT use in the ED substantially increased. CT abdomen and CT chest were the two most common studies performed and are potential targets for interventions to improve the appropriateness of CT use. © 2014 Lippincott Williams and Wilkins.