Several plants of the Ericaceae family produce grayanotoxins which can poison humans. The best-known of these intoxications involves the eating of 'mad honey (deli bal in Turkish)' contaminated by Rhododendron nectar grayanotoxins. Accounts of mad honey intoxication date back to 401 BC. It is still one of the common food intoxications encountered for humans and livestock in Turkey. Mad honey intoxication's symptoms are dose-related. In mild form, dizziness, weakness, excessive perspiration, hypersalivation, nausea, vomiting and paresthesias are present and close follow-up is enough. However, severe intoxication may lead to life threatening cardiac complications such as complete atrioventricular block that can be treated intravenously. In this review, properties and sources of grayanotoxins, their detection methods and mad honey intoxication are discussed.