BACKGROUND Stroke-like migraine attacks after radiation therapy (SMART) syndrome is a rare complication of cerebral radiation therapy that usually presents>10 years after treatment as reversible paroxysmal episodes of neurological dysfunction associated with headaches. CASES We report here on two cases of SMART syndrome in long-term survivors of high-grade glioma for whom neuropathological data were available. The course of the disease was unfavorable. Although the clinico-radiological picture of SMART syndrome clearly differs from classic cerebral radionecrosis, the gross neuropathological lesions observed in our two patients appeared to be similar to those described in focal radionecrosis. CONCLUSION SMART syndrome may progress from a benign reversible form to a severe and eventually irreversible form. This severe course may also be confused with tumor progression, and lead to permanent disability and inadequate antitumor treatment. Clinicians should be aware of this latter atypical presentation.