A minicomputer-based system was described that allowed real-time construction and simultaneous display, in flicker-free movie format, of a cardiac-cycle-spanning sequence of ECG-gated scintigraphic images. In as little as 2 min, the endless-loop flicker-free movie clearly displayed cardiac anatomy, time-dependent volume variations in cardiac chambers and abnormalities of cardiac wall motion that would be difficult or impossible to detect from static gated images. Simultaneously, a time-activity curve with high temporal resolution was generated from a previously defined region of interest, thereby quantifying additional parameters of cardiac function. Because the movie and time-activity curve were displayed in real time and required only a short data-collection interval to achieve statistical reliability, the system can be used interactively, modifying the form, intensity or duration of diagnostic and therapeutic interventions based on the observed response. This system was well suited for intervention studies, continuous cardiac monitoring and the rapid screening of patients with suspected cardiac disease.