• Nine volunteer subjects were tested with intravenously administered cocaine hydrochloride in doses ranging from 4 to 32 mg, as well as 10 mg of dextroamphetamine sulfate. Measures of cardiovascular and subjective effects were made. Generally parallel dose-effect functions were obtained for heart rate, blood pressure, Addiction Research Center Inventory scores, Profile of Mood Scales, and subject ratings. A substantial effect on each of these variables was recorded after 8 mg of cocaine. The increase continued and peaked at approximately 16 mg after which it usually leveled off. Ten milligrams of dextroamphetamine generally had an effect comparable to 8 to 16 mg of cocaine.