Diffusion-weighted (DW) magnetic resonance imaging (MRI) has already gained status in the neuroradiological MRI approach of a patient suffering from a variety of neurological diseases. The clinical application of DW MRI in the evaluation of renal disease is not standard. This manuscript describes preliminary results of the application of DW imaging in renal infection to aid differential diagnosis and/or lesion detection in clinical MRI. Three patients with acute pyelonephritis and two patients with renal abscess (one with xanthogranulomatous pyelonephritis, the other with a solitary pyogenic renal abscess) were examined with MRI. Areas of acute pyelonephritis and abscedation have restricted proton diffusion and are demonstrated on the DW images. Refinement of the technique, in-depth investigation of the pathological background of the MR findings and evaluation of its true clinical value need further investigation. This manuscripts shows preliminary findings of DW imaging in patients with renal infectious disease.