It has already been shown that both consolidation and reconsolidation of long-term memories require protein synthesis and de novo gene transcription immediately after training or mnemonic trace reactivation sessions. A few studies have also shown that consolidation of long-term memories also requires a late second wave of de novo gene transcription. Does such a requirement also occur for reconsolidation? By using two different mRNA synthesis inhibitors, we show that blockade of hippocampal late gene expression during a restricted post-training or postretrieval time window hinders the retention of long-term spatial memory for the Morris water maze task without affecting the functionality of the hippocampus. Our results indicate that spatial memory consolidation induces the activation of the late hippocampal genes transcriptional machinery and suggests a late gene expression-dependent reconsolidation process that operates in the dorsal hippocampus to stabilize the reactivated mnemonic trace.