The purpose of this study is to report different patterns of visual cortex activation in patients with Sturge-Weber syndrome as compared with healthy control subjects. Utilizing a visual paradigm of flashing lights, three children with Sturge-Weber syndrome were studied with functional magnetic resonance imaging. The results are compared with those documented in eight normal sedated children, and six young adult awake volunteers, using the same paradigms. All adult volunteers manifested bilateral activation in primary visual cortex (Brodmann's 17 and 18 areas). Two of them also had activation in secondary visual cortex (Brodmann's 19 area). In the eight sedated normal children, seven manifested activation in primary visual areas. The last exhibited no activation. The patients with Sturge-Weber syndrome demonstrated in the affected occipital lobe increased activation in one patient (11 months old), no activation in the second (12 years of age), and abnormal distribution of the activation in the third (11 months old). This report demonstrates that the vascular malformation of Sturge-Weber syndrome does not necessarily prevent cortical activation in the expected occipital cortex and may be associated with different patterns of abnormal activation. Assessing cortical function with functional magnetic resonance imaging in patients with Sturge-Weber syndrome may be helpful in decisions of surgical management and counseling.