The same dose of cannabinol (CBN) or cannabidiol (CBD) further increased the attenuation of precipitated abstinence signs observed in morphine-dependent rats that also received an acute dose of delta 9-THC. By contrast, rotational behavior (turning), which is observed concomitantly in THC-treated rats during morphine abstinence, was not increased by CBN, but was potentiated by CBD. These data illustrate differences between psychoinactive cannabinoids in their interaction with delta 9-THC that might be relevant to possible clinical use of Cannabis in narcotic detoxification.