Lavender plants have been used for their cosmetic and biologic benefits for many centries. Extracts from Lavandula plants have been found to cause antimuscarinic effects by blocking sodium and calcium ion channels in in vitro and in vivo studies. We present a case of poisoning by ingestion of tea made from Lavender stoechas ( grass). The patient was admitted to our emergency department with supraventricular tachycardia due to anticholinergic syndrome triggered by drinking lavender tea. On electrocardiography, a narrow QRS complex tachycardia was evident. After carotid sinus massage, the patient immediately returned to sinus rhythm. There are no reported data about the toxicity of Lavender stoechas plants with respect to supraventricular tachycardia, anticholinergic syndrome or sympathetic nerve activity. (Keio J Med 61 (2) : 66-68, June 2012)