The role of the periaqueductal gray (PAG) in morphine conditioned taste aversion (CTA) was studied using male Wistar rats as subjects. Following the presentation of a novel saccharin solution, animals with or without a lesion of the PAG were intraperitoneally injected with either morphine, lithium, ethanol or fenfluramine. As evident by the amount of saccharin solution consumed on a subsequent presentation, a PAG lesion reversed a morphine CTA but not CTAs produced by the other drugs used. The results suggest that the PAG may in part mediate morphine CTA.