Objective: Many war-zone deployed post-9/11 veterans report negative mental health symptoms related to their military service, which can have consequences for physical health symptoms and the impact of physical health on functioning. The current study examined the longitudinal, bidirectional relationships between mental health symptoms and physical health functioning in veteran men and women, allowing for exploration of gender differences., Methods: A sample of 1032 post-9/11 veterans (women: n = 554; men: n = 478) who recently returned from a war-zone deployment completed self-report measures of posttraumatic stress disorder (PTSD) symptoms, depression symptoms, and physical health functioning at 3 time points spanning approximately 7 years. Gender-stratified longitudinal cross-lagged panel analyses were used to examine bidirectional relationships., Results: PTSD symptom severity was negatively associated with physical health functioning across time. For women, associations were reciprocal, such that those reporting poorer physical health functioning reported more severe PTSD symptoms at later time points. Men with greater PTSD symptom severity reported poorer physical health functioning at later time points, but there was no evidence of bidirectionality. Men and women with more severe depression symptoms reported worse later physical health functioning, which further exacerbated depression symptoms across time., Conclusions: Findings showed that individual differences in mental health symptoms both set the stage for and were impacted by physical health functioning in post-9/11 veterans. Although additional research is needed, the current study suggests that healthcare approaches that consider the whole person, such as through integration of mental and physical health treatments, may be particularly relevant for post-9/11 veterans., (Published by Elsevier Inc.)