Pregnant rats were intubated with 50 mg/kg of delta-9-tetrahydrocannabinol (THC) or with THC plus alcohol to determine if a low dose of alcohol (1 g/kg) would significantly increase blood levels of THC. On the basis of this study, a second study was conducted in which pregnant rats were intubated with THC (50, 25 or 0 mg/kg) plus alcohol (2, 1 or 0 g/kg) from gestation day six to parturition. THC reduced birth weights but did not significantly affect litter size or passive avoidance learning. Alcohol did not have a significant effect on offspring birth weight nor did it interact with THC to affect offspring.