The authors examined the relationship over time of posttraumatic stress disorder (PTSD) and depression symptoms in a sample of Gulf War veterans. A large sample (N = 2,949) of Gulf War veterans was assessed immediately following their return from the Gulf region and 18-24 months later. Participants completed a number of self-report questionnaires including the Mississippi Scale for Combat-Related PTSD (T. M. Keane, J. M. Caddell, & K. L. Taylor, 1988) and the Brief Symptom Inventory (L. R. Derogatis & N. Melisaratos, 1983) at both time points and an extended and updated version of the Laufer Combat Scale (M. Gallops, R. S. Laufer, & T. Yager, 1981) at the initial assessment. A latent-variable, cross-lag panel model found evidence for a reciprocal relation between PTSD and Depression. Follow-up models examining reexperiencing, avoidance-numbing, and hyperarousal symptoms separately showed that for reexperiencing and avoidance-numbing symptoms, the overall reciprocal relation held. For hyperarousal symptoms, however, the association was from early hyperarousal to later depression symptoms only.