Evidence suggests a role for monoubiquitination of histone H2B, a regulator of increased gene transcription, in memory formation. However, whether monoubiquitination of histone H2A (H2Aubi), a transcriptional repressor, is involved in memory formation has not been explored. We found global and gene-specific decreases in H2Aubi in the amygdala following fear conditioning. H2Aubi decreased at