Gadolinium-ethoxybenzyl-DTPA (Gd-EOB-DTPA) is a recently introduced experimental magnetic resonance (MR) contrast agent for hepatic imaging. Although liver enhancement has been investigated in a number of animal models, tolerance evaluations of Gd-EOB-DTPA injection have been limited. The authors investigated acute hepatotoxicity in an isolated perfused rat liver model, cardiovascular effects in the anesthetized rat, and potential immunogenicity of Gd-EOB-DTPA using detection of specific antibodies. Using perfused rat liver model, no significant deviation could be observed for functional parameters, liver enzymes, or potassium release, comparing Gd-EOB-DTPA to a control, but there was a significant choleresis (+250% bile flow). Hemodynamic effects of Gd-EOB-DTPA were observed after femoral bolus injection, but only with relatively high dosages (0.3-0.5 mmol/kg, 10-fold the likely clinical dose in humans). Experimental conditions, idealized for antibody induction, failed to cause an IgG immune response to Gd-EOB-DTPA in the intact rat. The results further support preliminary conclusions that Gd-EOB-DTPA is a well-tolerated MR contrast agent.