A 12 year old boy presented with an acute onset of anisocoria and blurred vision. Ocular motility was normal but his right pupil was dilated, round but sluggishly reactive to light. There was no history of trauma, eye drops' instillation, nebulised drugs or local ointments. His past medical history was negative.A third nerve palsy was considered but the performed cerebral MRI was normal.On further anamnestic investigation the boy revealed that he had spent the morning doing gardening, and especially working on a "trumpet plant". Datura and Brugmansia are well known toxic plant; all Datura and Brugmasia plants contain, primarily in their seeds and flowers, tropane alkaloids such as scopolamine, hyoscyamine and atropine. Systemic and local intoxications have already been described.The day after anisocoria was much less evident and completely resolved in three days.We present this case of an unusual cause of mydriasis to underline once more the importance of a well and deeply conducted medical history.