The effects of intracoronary administration of contrast materials on regional and global left ventricular (LV) function were assessed in anesthetized dogs with segmental myocardial ischemia produced by critical stenosis of the circumflex coronary artery. Effects caused by sodium meglumine diatrizoate (R76), sodium meglumine calcium metrizoate (ISO), and metrizamide were evaluated. In the nonischemic state R76 produced an early (0-10 seconds) decrease in LV contractility followed by a late (10-20 seconds) positive inotropic effect. In the presence of regional ischemia there was prolongation of the negative inotropic effect. ISO produced only positive inotropic effects without significant differences between responses in the nonischemic and ischemic states. Metrizamide produced almost no alterations in LV function.