Background: The symptoms of mad honey poisoning resemble those of cholinergic toxidromes; however, it is not clear whether they share a common biochemical basis. Objectives: The aim of this study was to investigate a possible resemblance between mad honey poisoning and cholinergic toxidromes. Methods: This is a descriptive study performed prospectively in patients presenting to a University Medical Faculty Emergency Medicine Department emergency service with mad honey poisoning over 1 year, from September 2008 to September 2009. Adult patients with clinical findings suggesting mad honey poisoning (i.e., bradycardia, hypotension, syncope, and vertigo) and with a history of honey consumption were enrolled. Pseudocholinesterase levels in blood samples taken from the mad honey-poisoned patients were analyzed to determine whether these were lower than normal pseudocholinesterase levels for adults (5400-13,200 U/L). Results: The most common symptoms of the 30 patients enrolled in the study were vertigo and nausea. Low blood pressure and bradycardia were the most frequently observed physical examination findings. None of the patients enrolled had a history of disease that might cause low pseudocholinesterase. Mean pseudocholinesterase levels in our patients with mad honey poisoning were 7139.30 +/- 2316.41 U/L (min-max: 1785-12,835). Blood pseudocholinesterase levels were within normal limits in 90% of patients and below normal in 10%. Conclusion: A low pseudocholinesterase level was found in 3 (10%) of our 30 patients. These biochemical data do not support the hypothesis that mad honey poisoning should be regarded as cholinergic poisoning. (C) 2012 Elsevier Inc.