The effects of in utero administration of ethanol on single patterned alternation (PA) and the partial reinforcement extinction effect (PREE) were studied in 15-day-old rat pups. This fetal-alcohol treatment had no effect on PA but eliminated the PREE by reducing persistence in extinction after partial reinforcement (PRF) training to its level after continuous reinforcement (CRF) training, which was not affected by the treatment. The results are discussed in terms of prenatal damage to the hippocampus and in relation to an earlier experiment (Lobaugh, Bootin, & Amsel, 1985), which found no effect of infant hippocampal lesions on PA but an elimination of the PREE, which, unlike the fetal-alcohol case, resulted from PRF-like persistence in extinction following CRF training.