This study retrospectively reviewed records from current members of the U.S. military who had completed the PTSD Checklist (PCL) at 0 and 3-months after returning from deployments. Insomnia was the most commonly reported symptom of PTSD on the PCL and had the highest average severity scores. At initial screen, 41% of those who had been to Iraq or Afghanistan reported sleep problems. Those who had initially reported any insomnia had significantly higher overall scores for PTSD severity at follow-up than did service members without such a complaint. These results show that insomnia is a particularly frequent, severe, and persistent complaint in service members returning from deployment. Such complaints merit particular attention in relation to the possibility of PTSD.