OBJECTIVES/SPECIFIC AIMS: Given the heightened risk for suicide seen in individuals with PTSD+MDD, this report explored the effect of repeated ketamine infusions on SI in a cohort of veterans. METHODS/STUDY POPULATION: Veterans with PTSD+MDD (n = 15) received six intravenous infusions of 0.5 mg/kg ketamine on a Monday-Wednesday-Friday schedule over a 12-day period. All subjects endorsed SI at baseline. Outcome measures included the Montgomery-Asberg Depression Rating Scale (MADRS) total score, MADRS suicidal ideation item, and PTSD symptom Checklist for DSM-5 (PCL-5) subscales (intrusion, avoidance, negative alterations in cognition and mood, and marked alterations in arousal and reactivity), and visual analog scale of pain. Measures were collected immediately before and 24-hours after each infusion. RESULTS/ANTICIPATED RESULTS: Significant improvement in SI was observed 24-hours after the first infusion (Z = 3.21; p = .001) and remained significantly improved at all other post-infusion time points. Improvement in SI at the conclusion of the infusion series was significantly correlated with PTSD subscales of avoidance (r(12) = .610, p = .021), negative alterations in cognition and mood (r(12) = .786, p = .001), alterations in arousal and reactivity (r(12) = .729, p = .003), and pain (r(12) = .591, p = .013), even when controlling for improvement in symptoms of depression. DISCUSSION/SIGNIFICANCE OF IMPACT: The present analysis provides evidence of improvement in SI in a cohort of veterans with PTSD+MDD. Improvements in suicidality were correlated with PTSD symptom subscales and pain independent of improvement in depression. This report extends the interpersonal theory of suicide as it applies to posttraumatic pathology by demonstrating a significant association between improvements in all subclusters of PTSD, improvement in pain and improvement in suicidal ideation.