Aim Radiographic testing has an important role in the diagnosis and evaluation of pneumonia. The aim of the present study was to evaluate the usefulness of computed tomography (CT), in comparison with chest roentography (CR), in the diagnosis and evaluation of nursing‐ and healthcare‐associated pneumonia (NHCAP) . Methods The utility of CT in the diagnosis of NHCAP was compared with that of CR in a prospective study of patients who visited the emergency room in Nissan Tamagawa Hospital, Tokyo, Japan, with clinical symptoms that were indicative of NHCAP. We also evaluated whether particular CT findings were risk factors for NHCAP‐associated mortality. Results A total of 162 patients with suspected NHCAP were included in the study. The 162 patients included 147 (90.6%) patients who were diagnosed with NHCAP based on the detection of pneumonic infiltration on CT. In contrast, CR was not capable of recognizing pneumonic infiltration in 15 of the 147 (10.2%) patients. A multivariable analysis which was carried out to determine the risk factors for NHCAP‐associated mortality, showed that oxygen desaturation had the greatest odds ratio, followed by a blood urea nitrogen level of ≥21 mg/dL and the detection of bilateral pneumonic infiltration by CT. Conclusions We herein show that CT is superior to CR for the diagnosis and evaluation of NHCAP. The present study will provide a foundation for further studies to clarify whether the use of CT in the diagnosis and evaluation of NHCAP can improve the clinical outcome of patients with NHCAP. Geriatr Gerontol Int 2017; 17: 41–47.