The present study attempts to better understand the mechanism of injuries associated with direct lightning strikes. We reviewed the records of 256 individuals struck by lightning between 1965 and 1999, including 56 people who were killed. Basal skull fracture, intracranial haemorrhage, pulmo-nary haemorrhage, or solid organ rupture was suspected in three men who died. Generally these lesions have been attributed to current flow or falling after being struck. However, examination of surface injuries sustained suggested that the true cause was concussion secondary to blast injury resulting from vaporization of water on the body surface by a surface flashover spark. To investigate this hypothesis, an experimental model of a lightning strike was created in the rat. Saline-soaked blot-ting paper was used to simulate wet clothing or skin, and an artificial lightning impulse was applied. The resultant lesions were consistent with our hypothesis that the blast was reinforced by the con-cussive effect of water vaporization. The concordance between the clinical and experimental evidence argues strongly for blast injury as an important source of morbidity and mortality in lightning strikes.