Objectives: Telomere length (TL) is a robust indicator of cellular aging. TL erosion has been associated with exposure to social and traumatic stressors. Loneliness and perceived social support are strongly linked to increased morbidity and mortality, but have yet to be investigated in relation to TL after extreme stress. The present study examined whether loneliness and lack of perceived social support following wartime captivity may be associated with TL as repatriated prisoners of war (ex-POWs) enter old age and contribute to its prediction. Method: A cohort of Israeli ex-POWs from the 1973 Yom Kippur War (n = 83) were assessed. Questionnaires were utilized to assess loneliness and perceived social support 18 years after the repatriation (T1), and Southern blotting was used to measure TL 24 years later (T2). A zero-order Pearson correlation test and a hierarchical regression analysis were utilized in order to examine the research questions. Results: Loneliness and lack of perceived social support each significantly predicted shorter TL in later life, and together added 25.8% to the overall explained variance. Conclusions: This is the first study to empirically demonstrate that loneliness and lack of perceived social support in early adulthood may be associated with shorter TL during transition to old age in a population that has endured extreme stress. Although the study design precludes causal inferences, several psychobiological mechanisms may explain the findings. The potential clinical significance of social deficits for longevity and heath in related populations is therefore addressed, and an agenda for future investigations is suggested.