Shortening of telomere length is a biological mark of increasing age. This study looked at the effects of pessimistic orientation on average leukocyte telomere length (LTL) at multiple time points, as well as effects on the rate of change in LTL over time. Higher pessimistic orientation scores were associated with shorter average LTL, even when adjusting for healthier subjects being more likely to return for follow-up visits. However, pessimistic orientation scores were not associated with rate of change of LTL over time, and no associations were found between optimism scores and LTL.