To evaluate the usefulness of dynamic MRI of kidneys in healthy volunteers and patients with different 24-hour creatinine clearance (Ccr) levels, a dynamic study that employed the T2* weighted gradient echo technique (FLASH : TR/TE=34/25msec,flip angle=20 degrees) with single images during breathhold was performed on 10 healthy volunteers and 35 patients, all examined for the Ccr and suspected of having renal parenchmal disease after a phantom study. T1-weighted and dynamic MR imagings were obtained with a 1.5T imager.I andalyzed the time-intensity curve of renal cortex and medulla, and defined a cortex decreased ratio (CDR) and medulla decreased ratio (MDR) in comparison with the Ccr. The cortico-medullary difference ratio (CMDR) of T1WI were better correlated with the Cce. The parameters of the T2* dynamic MRI study (CDR, MDR) were better correlated with the Ccr than CMDR. Renal function can be quantitatively evaluated with the T2* dynamic MRI and there ia s possibility that we can qualitatively evaluate the renal dysfunction and estimate its cause.