['Although alcohol problems are common in military personnel, data examining the relationship between psychiatric conditions and alcohol abuse occurring de novo peri-/post-deployment are limited. We examined whether pre-existing or coincident depression and post-traumatic stress disorder (PTSD) predicted new onset peri-/post-deployment alcohol abuse among Ohio Army National Guard (OHARNG) soldiers.', 'We analyzed data from a sample of OHARNG who enlisted between June 2008 and February 2009. Participants who had ever been deployed and who did not report an alcohol abuse disorder prior to deployment were eligible. Participants completed interviews assessing alcohol abuse, depression, PTSD, and the timing of onset of these conditions. Logistic regression was used to determine the correlates of peri-/post-deployment alcohol abuse.', 'Of 963 participants, 113 (11.7%) screened positive for peri-/post-deployment alcohol abuse, of whom 35 (34.0%) and 23 (32.9%) also reported peri-/post-deployment depression and PTSD, respectively. Soldiers with coincident depression (adjusted odds ratio [AOR]=3.9, 95%CI: 2.0-7.2, p<0.01) and PTSD (AOR=2.7, 95%CI: 1.3-5.4, p<0.01) were significantly more likely to screen positive for peri-/post-deployment alcohol abuse; in contrast, soldiers reporting pre-deployment depression or PTSD were at no greater risk for this outcome. The conditional probability of peri-/post-deployment alcohol abuse was 7.0%, 16.7%, 22.6%, and 43.8% among those with no peri-/post-deployment depression or PTSD, PTSD only, depression only, and both PTSD and depression, respectively.'] Do coincident posttraumatic stress disorder and depression predict alcohol abuse during and after deployment among Army National Guard soldiers?