Some of the limitations of CT in the diagnosis of neurologic disease are reported. Problem areas include small lesions; lesions obscured by adjoining structures; small vascular structures and detail of large vessels; cases in which the diagnosis is made but information is incomplete for treatment; cases of incorrect diagnosis; non-nenoplastic lesions mistaken for neoplasms; some subdural hematomas; occasional false negative findings; and misinterpretation due to technical errors. Knowledge and use of the clinical presentation, the performance of other complementary diagnostic procedures, repeat CT scans tailored to the region of interest, and repeat serial scans may assist in reaching the proper diagnosis and diminishing potential error.