Prenatal aluminum exposure may affect the development of the embryo and alter the capacity for learning and memory in adults. The chick embryo is a good experimental model to study the effect of prenatal toxin exposure on cognitive defects in offspring, because it eliminates maternal confounding variables. In the present study, we applied a one-trial passive avoidance-learning task in day-old chicks to examine the effects of prenatal aluminum chloride injections (2, 20, and 200 mM in 200 μl per egg, daily over a period of 4 successive days) on memory consolidation. The data suggest that chicks injected with aluminum chloride (20 mM) daily from E12 to E15 had significantly impaired short-term memory, intermediate-term memory, and long-term memory (LTM) after training (p < .05) but chicks injected with aluminum chloride (2 mM) had impaired LTM only. © 2011 Wiley Periodicals, Inc. Dev Psychobiol 54:133-138, 2012.