In the present study, normal laboratory rats (n = 22), were injected intravenously with water soluble contrast media (CM) or saline. Renal function was monitored before and followed after challenge. Seven animals were injected with saline, the others with 3 different types of contrast media. The absolute urinary creatinine output decreased significantly in the saline group, from 0.0247 mumol/min 100 g BW (IR: 0.0052) to 0.0167 mumol/min 100 g BW (IR: 0.0019) (p < 0.01), while in the CM groups only a significant decrease was seen after ioxaglate injection, from 0.0250 mumol/min 100 g BW (IR: 0.0014) to 0.0174 mumol/min 100 g BW (IR: 0.0027) (p < 0.01). ANOVA between the groups showed no difference. The median values for serum creatinine after injection of the test products did not differ from the control values. It seems therefore that the challenge of a normal laboratory rat with CM is not a suitable model for the detection of subtile nephrotoxic properties of CM.