Abstract: Objective To evaluate the changes in renal oxygenation in rats with acute aristolochic acid nephropathy using blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) at 7.0T. Methods Wistar rats were randomly divided into AAN group (n=18) and control group (n=6) for intraperitoneal injections of AAI at 40 mg/kg and PEG400, respectively, on a daily basis for 6 consecutive days. All the control rats and 6 rats from AAN group underwent BOLD MRI scan before and at 2, 4, and 6 days after the initial injection for measuring renal cortical and medullary R2* values. At each of the 4 time points, 3 rats in AAN group were sacrificed for histological evaluation; the control rats were examined at 6 days after the initial injection. Results The cortical and medullary R2* values of the rats in AAN group on days 4 and 6 were significantly higher than those in the control group (P<0.05). In AAN group, the cortical R2* values showed no obvious changes on day 2 as compared with the baseline values, but increased significantly on day 4 (P<0.05) and day 6 (P<0.01); the medullary R2* values increased progressively and were significantly higher than the baseline values on day 4 (P<0.01) and day 6 (P<0.01). In the control group, no significant changes were detected in either cortical or medullary R2* values throughout the experiment. Conclusion BOLD MRI allows non-invasive measurement of renal oxygenation levels in rats with AAN. The increase of renal cortical and medullary R2* values, and particularly the latter, indicates a lowered renal oxygenation level, which provides potentially useful information for clinical decisions.