fMR imaging is a versatile technology that allows for the noninvasive identification of sensory, motor,and cognitive functions that may be impaired by surgical resection. fMR imaging provides the capacity to probe several brain functions, and when results are uncertain, to repeat or modify them. There are some limitations, MR contraindications to scanning, motion, and cooperation among them. Yet for most patients fMR imaging provides a reliable way to lateralize language dominance and to guide localization of language functions. Memory paradigms lag behind language in practical application, but the impediments to its utility will likely be resolved in the near future.