The Spanish version of the 49-item short form of the Addiction Research Center Inventory (ARCI) was assessed in simulated drug conditions. After the translation process was completed, the questionnaire was administered to forty-five adult polydrug abusers who were residing in a general hospital. Subjects answered the questionnaire on four occasions, describing the feelings they usually experienced under the effects of four classes of drugs of abuse (morphine-like opioids, alcohol, stimulants and hallucinogens). The scales showed an acceptable level of internal consistency. A characteristic pattern of response was obtained for each condition. A discriminant analysis revealed that four scales PCAG (pentobarbital-chlorpromazine-alcohol group), MBG (morphine-benzedrine group), LSD (lysergic acid dyethylamide scale) and BG (benzedrine group) significantly discriminated between the conditions studied. Sixty percent of the questionnaires answered were correctly classified according to the discriminant functions constructed. The results from this study are similar to those obtained with the English ARCI, and suggest that the Spanish version of the 49-item ARCI may be an useful instrument for the evaluation of subjective effects produced by psychoactive drugs in Spanish populations.