The purpose of the study was to determine the feasibility of international teleradiology, utilizing day-night time differences, for online interpretation of overnight computed tomography (CT) studies. One hundred and two consecutive Emergency Room patients who underwent CT examinations between the hours of 11 pm and 7 am were enrolled. All age groups and study types were included. CT studies were transmitted from the in-hospital PACS system (Kodak, Fremont, Calif.) to a web-based server (Medweb, San Francisco, Calif.). A radiologist in Bangalore, India, working an 8 amto 4 pm day shift, downloaded and reviewed the studies on a desktop PC using a 128-kbps internet connection at 10-20:1 wavelet compression and generated a report. The report was then uploaded to the server, noting the time at upload. Each study report was compared with the official in-house diagnostic report and concordance assessed on a three-point scale. Mean download time was 8.14 s per image. For head CT reports ( n=47), the mean turnaround time for a final transcribed report was 39.5 min. For abdomen/pelvis CT reports ( n=48) the mean turnaround time was 84.4 min. Out of 106 cases, there was discordance between the clinical diagnostic report and the study report in 20 (19%); however, on subsequent review the teleradiology report was found to be correct in 13 of these. Day-night time differences across the globe can be utilized to provide overnight emergency radiology coverage using web-based teleradiology. Scan download and report upload times are within acceptable limits.