This pilot study evaluates the effectiveness and safety of serial ketamine infusions in veterans with treatment-resistant depression (TRD) and chronic post-traumatic stress disorder (PTSD). Acknowledging the intricate link between depression, trauma, and the heightened suicide risk in veterans with both conditions, the study explores ketamine's rapid antidepressant and PTSD symptom-relieving properties. Participants, male and female veterans aged 18 to 75 from various military backgrounds, will undergo six ketamine infusions across two weeks, followed by a two-month follow-up. This research aims to provide new insights into managing complex mental health challenges in veterans.