Contrast materials cause numerous effects on the cardiovascular system. The major direct actions on the heart are myocardial mechanical and electrophysiological alterations. The major direct action on the peripheral circulation is vasodilation. The indirect effects, for the most part, are reflexly mediated and tend to offset the direct effects. The author reviews the various experimental models and techniques used for assessing the actions of contrast materials on the cardiovascular system. The salient findings from previous studies using various experimental models are discussed.