Gulf War Illness (GWI), Myalgic encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and Post Treatment Lyme Disease (PTLD) have significant symptom overlap, which suggest studying them in parallel may enable discovery of common triggers for disease in addition to diagnostic and prognostic biomarkers, and insights that can lead to therapeutic interventions. We are analyzing the metabolomic profiles of Gulf War veterans with and without Gulf War Illness (GWI) to determine disturbances that provide insights to GWI and similar diseases. During this reporting period, we analyzed metabolomic data on plasma for primary metabolites, biogenic amines, and complex lipids. We identified two dipeptides significantly elevated and one primary metabolite significantly reduced in veterans with GWI. Sphingomylins, a major component of cell membranes, were significantly reduced in veterans with GWI. A reduction in sphingomylins has also been identified in ME/CFS patients, which supports a dysregulation in lipid metabolism for both conditions.