Background Studies in male combat veterans have suggested posttraumatic stress disorder (PTSD) is associated with shorter telomere length (TL). We examined the cross‐sectional association of PTSD with TL in women exposed to traumas common in civilian life. Methods Data are from a substudy of the Nurses’ Health Study II (N = 116). PTSD and subclinical PTSD were assessed in trauma‐exposed women using diagnostic interviews. An array of health behaviors and conditions were assessed. DNA was extracted from peripheral blood leukocytes (collected 1996–1999). Telomere repeat copy number to single gene copy number (T/S) was determined by quantitative real‐time PCR telomere assay. We used linear regression models to assess associations and examine whether a range of important health behaviors (e.g., cigarette smoking) and medical conditions (e.g., hypertension) previously associated with TL might explain a PTSD‐TL association. We further examined whether type of trauma exposure (e.g., interpersonal violence) was associated with TL and whether trauma type might explain a PTSD‐TL association. Results Relative to not having PTSD, women with a PTSD diagnosis had shorter log‐transformed TL (β = −.112, 95% confidence interval (CI) = −0.196, −0.028). Adjustment for health behaviors and medical conditions did not attenuate this association. Trauma type was not associated with TL and did not account for the association of PTSD with TL. Conclusions Our results add to growing evidence that PTSD may be associated with more rapid cellular aging as measured by telomere erosion. Moreover, the association could not be explained by health behaviors and medical conditions assessed in this study, nor by type of trauma exposure.