PURPOSE: To evaluate the differences in MR findings of metastatic adenocarcinoma and non-adenocarcinoma of thebrain. MATERIALS AND METHODS: We retrospectively analyzed MR findigns of metastatic brain tumors in 32 patients;in all cases, pathologic diagnosis was estabilished by biopsy or surgical resection. The signal intensities ofbrain lesions on multiple pulse sequences were compared. The enhancement patterns, degree of peritumoral edema,and number and size of brain lesions were also compared. RESULTS: The study group consisted of 19 patients withmetastatic adenocarcinoma and 13 with metastatic non-adenocarcinoma ; there were 64 adenocarcinomas and 45non-adenocarcinomas. On T1WI, the signal intensity of the lesions was hypointense, isointense, and hyperintense in57.8%, 39.0%, and 3.2% of adenocarcinomas; and 84.5%, 13.3%, and 2.2% of non-adenocarcinomas, respectively. OnT2WI, signals were hyperintense, isointense, hypointense, and heterogeneous in 67.2%, 10.9%, 17.2%, and 4.7% ofadenocarcinomas ; and 80%, 0%, 8.9%, and 11.1% of non-adenocarcinomas, respectively. On T2WI, seven of 19 patientswith adenocarcinoma and two of 13 with non-adenocarcinoma were either hypo- or isointense relative to the whitematter. In the adenocarcinoma group, hypo- or isointensity was seen in four cases of gastrointestinal cancer, twoof lung cancer, and one of endometrial cancer ; in the non-adenocarcinoma group, this was seen in retroperitonealembryonal carcinoma and small cell carcinoma of the lung. Two cases of adenocarcinoma showed hypointensity on T2WIand hyperintensity on TIWI, and this was probably related to the presence of blood products. On histopathology,one case of adenocarcinoma showing hypointensity on T2WI was shown to contain mucin. CONCLUSION: When brainmetastasis shows hypo- or isointensity on T2WI, adenocarcinoma is more likely than non-adenocarcinoma.