Background: The aim of this study was to investigate the distribution of the c-erbB2 antisense probe labeled with superparamagnetic iron oxide nanoparticles in the major organs of mice by MR imaging. Methods: Sixty BALB/c mice were randomly divided into experimental and control groups. MR scans were performed in each mouse of the experimental group at five different time points (10, 30, 60, 180 and 360 min) after injection of the antisense probe. The signal from each major organ (liver, spleen, heart, kidney and muscle tissue) in comparison with the background signal (signal to noise ratio) was determined at each time point as a measure of the distribution of the antisense probe. Six control mice were killed at each of the same time points and the organs immediately removed for determination of their iron content. Results: After injection of the antisense probe, the highest enrichment of the probe was seen in the spleen, reaching a peak at 180 min, followed by the liver, muscle, heart and kidney. Conclusions: MR imaging can visualize the distribution of c-erbB2 antisense probe labeled with superparamagnetic iron oxide nanoparticles in the major organs of mice, and this may provide the basis for further in vivo studies of MR imaging time and dose selection.