Cardiac computed tomography (CT) has evolved into an effective imaging technique for the evaluation of coronary artery disease in selected patients. Two distinct advantages over other noninvasive imaging modalities include its ability to evaluate directly the coronary arteries and to provide an opportunity to evaluate extracardiac structures, such as the lungs and mediastinum. Some centers reconstruct a small field of view (FOV) cropped around the heart, but a full FOV (from skin to skin in the irradiated area) is obtainable in the raw data of every scan so that clinically relevant noncardiac findings are identifiable. Debate in the scientific community has centered on the necessity for this large FOV evaluation. A review of noncardiac structures provides the opportunity to make alternative diagnoses that may account for the patient's presentation or to detect important but clinically silent problems such as lung cancer. Critics argue that the yield of biopsy-proven cancers is low and that the follow-up of incidental noncardiac findings is expensive, resulting in increased radiation exposure and possibly unnecessary further testing. In this two-part review we outline the issues surrounding the concept of the noncardiac read looking for noncardiac findings on cardiac CT. Part I focuses on the pros and cons of the practice of identifying noncardiac findings on cardiac CT.