Objective     To assess the imaging effect of renal trauma by using the ultrasound contrast agent and the second harmonic imaging in rabbit model and provide the basic experimental data for the clinical purpose using ultrasound contrast in renal injury.      Methods     Twelve New Zealand white rabbits were used to establish animal model with the left renal blunt injury. The imaging of hematoma and the enhancement effect of the gray scale imaging of renal parenchyma around hematoma were observed before and after the contrast by lipid-encapsulated perfluorocarbon contrast agent into the ear veins. The contrast effect was assessed by video analysis. The variability of the difference between the hematoma and the renal parenchyma was analyzed before and after contrast.       Results     The hematomas were seen incompletely with vague margin in 9 cases before the contrast

absent in other 3 cases. After the contrast

all hematomas in 12 cases were displayed clearly and completely. The gray scale of the hematoma areas appeared no significant difference (P0.05) before and after the contrast. However

for the renal parenchyma

it increased significantly after the contrast (P0.01).      Conclusion     The use of the ultrasound contrast agent could help to distinguish hematoma from the normal renal parenchyma in renal trauma. This technique provides a new mean in the diagnosis of the renal trauma.