Fifteen cases of presumed cocaine intoxication were evaluated in the emergency room (ER) at a city hospital over a four-day period. This series is unique in that many of these patients were from a similar area of the city, in some cases had the same street address, were regular abusers of cocaine, and presented to the ER with similar symptoms of tachycardia, dilated pupils, marked confusion, bizarre and sometimes violent behavior, psychosis, and hallucinations. Many of these symptoms were present several hours after drug use. Samples of a white powder presumed by the patients to be cocaine were obtained from two patients and analyzed by gas-liquid chromatography. Neither sample contained cocaine, but rather revealed atropine, benzocaine, and procaine. The signs and symptoms of cocaine, amphetamine, and atropine intoxication are reviewed and the problems of drug analysis and differential diagnosis of drug intoxication are discussed.