The intermediate and medial hyperstriatum ventrale (IMHV) of the chick brain is a site of recognition memory for filial imprinting. Previous results have demonstrated learning-related changes in the amounts of the three major isoforms of neural cell adhesion molecule (NCAM) in the left IMHV. The increases were present 24 h after training. The present study enquired whether the increases persisted and were present 48 h after training. The brain regions analysed were the left and right IMHV and the left and right hyperstriatum accessorium (HA), a visual projection area. The alpha-subunit of calcium/calmodulin protein kinase II (CaMKIIalpha) was also assayed. There were significant correlations between a measure of the strength of learning and the amount of NCAM 180 in the right IMHV (r = +0.65; p = 0.012) but not in the left, and in the left HA (r = -0.61; p = 0.02), but not in the right. There were no learning-related changes for CaMKIIalpha. We conclude that in IMHV the effects of imprinting on NCAM 180 are expressed mainly in the left IMHV 24 h after training, but 48 h after training are expressed mainly in the right IMHV.