An interactive real-time spiral gradient-echo and an interactive real-time radial steady-state free precession sequence were investigated for the quantitative assessment of left ventricular function. Data were acquired in 18 patients without electrocardiographic triggering and breath holding. With the interactive real-time spiral gradient-echo sequence, significant underestimation of endocardial and epicardial volumes was demonstrated; with the interactive real-time radial steady-state free precession sequence, excellent agreement was shown with standard cardiac-triggered segmented k-space breath-hold steady-state free precession MR imaging. Interactive real-time radial steady-state free precession imaging allows accurate quantitative assessment of left ventricular volumes.