BACKGROUND A broad spectrum of nonneoplastic conditions can mimic a brain tumor, both clinically and radiologically. In this review we consider these, taking into consideration the following etiologic categories: infection, demyelination, vascular diseases, noninfectious inflammatory disorders, and iatrogenic conditions. We give an overview of such diseases, which represent a potential pitfall for pathologists and other clinicians involved in patient care, and present selected cases from each category. OBJECTIVE To illustrate the radiologic and pathologic features of nontumoral intracranial lesions that can clinically and radiologically mimic neoplasia. METHODS Case-derived material and literature review. CONCLUSIONS A variety of nonneoplastic lesions can present clinically and radiologically as primary or metastatic central nervous system tumors and result in surgical biopsy or resection of the lesion. In such situations, the pathologist has an important role to play in correctly determining the nature of these lesions. Awareness of the entities that can present in this way will assist the pathologist in the correct diagnosis of these lesions.