Caffeine has long been recognized as an addictive substance with numerous toxic effects. Death due to caffeine overdose is rare, due in part to its marked gastric irritation resulting in spontaneous emesis. Caffeine can be found in food, beverages, analgesics, and over-the-counter weight loss products. We report a fatality resulting from the ingestion of mail order diet pills containing caffeine as their only active ingredient. A 22-year-old female arrived in the emergency department in cardiac arrest after ingesting these diet pills. Resuscitation efforts were unsuccessful. A serum toxicology screen revealed the presence of caffeine with a level of 1,560 micrograms/ml (lethal greater than 100 micrograms/ml). To our knowledge this is the highest reported fatal caffeine level. No other drugs were identified on the screen. Based on the absence of pathology on autopsy and the high caffeine level, death was attributed to acute caffeine toxicity. This case illustrates that deaths resulting from caffeine, although rare, continue to occur.