Rationale and Objectives. The authors compared the cardiovascular effects of gadodiamide injection and gadopentetate dimeglumine. Methods. Gadodiamide injection or gadopentetate dimeglumine, each at doses of 0.3 or 1.5 mmol per kilogram of body weight, or saline volume control was administered intravenously in the cephalic vein of anesthetized dogs. Hemodynamic parameters, electrocardiographic parameters, and peripheral flow were measured, Results. Neither the low nor high dose of gadodiamide injection caused statistically significant (P < .05) changes in any of the measured cardiovascular parameters. High doses of gadopentetate dimeglumine, however, significantly decreased left ventricular and systemic blood pressure and significantly depressed left ventricular contractility (P < .05). Conclusion. Gadodiamide injection caused no observable cardiovascular effects,, whereas high doses of gadopentetate dimeglumine caused cardiodepressive and hypotensive effects.