The authors report a mass poisoning incident involving "mad honey" on Réunion Island that occurred in 2008. Most patients presented with fainting, bradycardia, hypotension, and dizziness, consistent with ingestion of food containing grayanotoxins. All patients fully recovered with symptomatic treatment. A survey of the areas surrounding the hives where the honey was collected revealed the presence of large quantities of Agauria salicifolia (Ericaceae family), a plant endemic to the southwestern Indian Ocean and rich in grayanotoxins. A close relationship between these two events was strongly suspected. A monitoring system for honey production should be implemented. (R.A.)