Depressed patients discharged from psychiatric hospitalizations face increased risks for adverse outcomes including suicide, yet antidepressant adherence rates during this high-risk period are unknown. Using Veterans Affairs (VA) data, we assessed antidepressant adherence and predictors of poor adherence among depressed veterans following psychiatric hospitalization. We identified VA patients nationwide with depressive disorders who had a psychiatric hospitalization between April 1, 1999 and September 30, 2003, received antidepressant medication, and had an outpatient appointment following discharge. We calculated medication possession ratios (MPRs), a measure of medication adherence, within 3 and 6 months following discharge. We assessed patient factors associated with having lower levels of adherence (MPRs < 0.8) after discharge. The criteria for 3- and 6-month MPRs were met by 20,931 and 23,182 patients respectively. The mean 3 month MPR was 0.79 (SD = 0.37). The mean 6 month MPR was 0.66 (SD = 0.40). Patients with poorer adherence were male, younger, non-white, and had a substance abuse disorder, but were less likely to have PTSD or other anxiety disorders. Poor antidepressant adherence is common among depressed patients after psychiatric hospitalization. Efforts to improve adherence at this time may be critical in improving the outcomes of these high-risk patients.