A non-fatal case of Nerium oleander (common oleander) self-poisoning in a 45-year-old female is presented. Initial symptoms were nausea and vomiting, abdominal pain, phosphenes, cardiovascular shock and sinus bradycardia. Blood and urine were assayed for oleandrin, the major cardiac glycoside of N. oleander, using a highly specific HPLC/MS procedure. The blood concentration of oleandrin at admission was 1.1 ng/ml. This is the first report of an oleander intoxication ascertained by the mass spectrometric identification of oleandrin in blood. HPLC/MS appears to be the method of choice for the forensic-toxicological investigation of poisonings by cardiac glycosides.