Résumé : We hypothesized that induction of opiate antagonist-precipitated withdrawal under anesthesia can decrease the expression of later withdrawal signs. Three groups of morphine-dependent rats were compared in different experimental conditions of withdrawal precipitation using naloxone. We showed that anesthesia can temporarily overshadow the expression of withdrawal signs, but that some signs can be delayed and increased in intensity. This can be explained by a parallel and temporary effect of anesthesia on arousal and pain threshold. This carries important implications on the use of anesthesia in detoxification procedures.