The pRb (retinoblastoma protein) tumour suppressor protein has a crucial role in regulating the G1- to S-phase transition, and its phosphorylation by cyclin-dependent kinases is an established and important mechanism in controlling pRb activity. In addition, the targeted acetylation of lysine (K) residues 873/874 in the carboxy-terminal region of pRb located within a cyclin-dependent kinase-docking site hinders pRb phosphorylation and thereby retains pRb in an active state of growth suppression. Here, we report that the acetylation of pRb K873/874 occurs in response to DNA damage and that acetylation regulates the interaction between the C-terminal E2F-1-specific domain of pRb and E2F-1. These results define a new role for pRb acetylation in the DNA damage signalling pathway, and suggest that the interaction between pRb and E2F-1 is controlled by DNA-damage-dependent acetylation of pRb.