The frequency and degree of periportal high intensity (PHI) on T2-weighted images in 28 patients (32 MR studies) with acute viral hepatitis were analyzed with regard to the various levels of serum glutamic-oxaloacetic transaminase (SGOT) and clinical phases. Periportal high intensity was found in 16 of 32 MR studies (50%) and no definite PHI was found in 7 studies (22%). Periportal high intensity appeared when the SGOT level was >500 IU or when the phase of the disease was early. Follow-up studies revealed that PHI decreased during clinical recovery. We conclude that the degree of PHI on T2-weighted images reflects the severity of the disease in acute viral hepatitis.