Maternal dietary Zn deficiency during fetal development induces substantial cognitive dysfunctions in the resultant offspring. The mechanism underlying this effect is unclear. The present study evaluated whether the impairments caused by gestational and lactational Zn deficiency are mediated by the hippocampal calmodulin-dependent protein kinase II α (α-CaMKII)/brain-derived neurotrophic factor (BDNF) signalling pathway as well as whether they can be restored by postnatal Zn supplementation. Rats were randomly divided into four groups on the first day of pregnancy (n 12): control (CO) group; pair-fed (PF) group; Zn-deprived (ZD) group; orally Zn-supplemented group. The spatial memory of the offspring was tested at postnatal day 35 using the Morris water maze. Long-term potentiation (LTP) in the rat hippocampal medial perforant path-dentate gyrus pathway was evaluated simultaneously, and α-CaMKII and BDNF protein levels were examined by Western blot analysis. The results demonstrated that the ZD group exhibited a significantly longer latency period in the Morris water maze as well as a significantly decreased LTP amplitude compared with the CO and PF groups. α-CaMKII and BDNF protein expression in the hippocampus was significantly reduced in the ZD group. Postnatal Zn supplementation restored the cognitive dysfunction induced by gestational Zn deficiency but could not completely reverse the decreased LTP and α-CaMKII/BDNF protein levels. Our findings suggest that the α-CaMKII/BDNF signalling pathway may be involved in Zn deficiency-induced cognitive and synaptic impairments.