A total of 83 cases with ring enhancement in the cranial CT were radiologically analyzed to derermine thespecific CT findings of the primary and metastatic brain tumor, inflammatory disease, resolving hematoma, andcerebral infarction. The brief results are as follows. 1. Glioblastoma multiforme show a characteristic thick orthin irregular ring enhancement with significant mass effect and surrounding edema. Most of the metastatic tumorsalso show irregular thick or thin walled ring enhancement with significant surrounding edema. Tumoral hemorrhagewas observed in the metastatic melanoma, breast cancer, and lung cancer. 2. The brain abscess usually showcharacteristic thin regular and ring enhancement with different degree of surrounding edema. 3. Ring enhancementin resolving hematomas and cerbral infarctions usually occures about 10-30 days after the onset of symptoms, whichshows thin and regular ring pattern wihtout significant surrounding edema.