For military personnel, there are positive and negative aspects of marriage, which may contribute to mental health during times of high stress. The present study investigated the relationship of marital status with three mental health outcomes (general mental health, posttraumatic stress disorder [PTSD], depression) among 14,624 Canadian military personnel recently deployed in support of the mission in Afghanistan. Greater combat exposure was associated with poorer postdeployment mental health, but marital status was, on its own, only slightly associated with PTSD. Marital status significantly moderated the relationship between combat exposure and mental health: For both single and married participants, mental health declined as combat exposure increased, but this association was stronger for married members. This association could be due to the additional familial demands that married personnel may face upon their return from deployment or to the stresses associated with poor marital satisfaction. Overall, results suggest that the relationship between marital status and mental health after deployment is complex and may vary according to other factors.