A monoclonal antibody was used to examine changes in immunoreactivity of the cytoskeletal protein, alpha-tubulin, following passive avoidance learning in day-old chicks. Postmitochondrial fractions (16,000 g supernatants) were prepared from specific forebrain loci taken at several time points after training and assayed with the anti-alpha-tubulin antibody, YL1/2. Of the regions examined, elevations in the titre of YL1/2 were found in the left intermediate hyperstriatum ventrale 1 h, 6 h and 24 h following training, in the left lobus parolfactorius 1 h following training and in the right lobus parolfactorius 6 h and 24 h following training. No training-related changes were detected in a third forebrain region, the paleostriatum augmentatum. These results regarding the cellular dynamics of memory formation in the chick confirm and expand on earlier findings from our laboratory.