To characterize the relationship between findings on magnetic resonance (MR) images and histologic changes in chronic liver disease, a prospective study was performed in 100 patients with chronic hepatitis and cirrhosis and 28 healthy subjects. Biopsy specimens, obtained in all patients before MR imaging, were evaluated with the histologic activity (HA) index; MR images were obtained with short inversion time inversion-recovery (STIR) and spin-echo sequences. On STIR images, normal livers were iso-intense to fat. Significant differences (P < .001) existed between signal intensity of normal livers and that of diseased livers, which were brighter than normal livers on STIR images. The ratio of signal intensity of liver to that of fat on STIR images was associated with an HA index grouped by severity (P < .05): Patients with higher HA scores had a brighter liver. Signal intensity ratios on MR images were statistically significantly associated with periportal and lobular necrosis and portal inflammation. The signal intensity of liver on STIR images is associated with the degree of histologic severity in patients with chronic liver disease.