The similarities between the biomarkers of stress-induced premature senescence and replicative senescence are reviewed. The possibility of existence of 'molecular scars', i.e. long-term changes observed after subcytotoxic stress and not observed in replicative senescence, is considered. Lastly, the likeliness of existence of stress-induced premature senescence in vivo is discussed. The possible effects on normal and pathological tissue ageing are predicted.