In the initial years following the 1990-1991 Gulf War, reports of a complex array of medically unexplained symptoms began to emerge among U.S. Gulf War Veterans. This cluster of symptoms included fatigue, pain, gastrointestinal symptoms, respiratory symptoms, dermatological symptoms, neurological symptoms, and cognitive symptoms, and collectively became known as GWI. Although several war-related exposures have been associated with GWI, no single exposure has been confirmed as the causative agent, and no single treatment has been identified. There is no objective diagnostic test for GWI, and the International Classification of Diseases Manual (10th edition) has no diagnostic code for GWI. In 2022, the Sergeant First Class Heath Robinson Honoring our Promise to Address Comprehensive Toxics Act of 2022 or PACT Act was passed. Section 405 of this bill requires VHA personnel to review the evidence for GWI and provide an evidence-based screening questionnaire to be administered to Veterans who present with one symptom in the clinical setting. Efforts to characterize GWI into a case definition have produced several different definitions. While all are slightly different from each other with respect to symptom severity, the types of symptoms, the number of symptoms required, and exclusionary medical conditions, all the proposed definitions require the symptoms to be chronic and, at minimum, include symptoms from the following domains: pain, fatigue, and neurocognitive. The GWI symptom screening questionnaire developed by VA HOME is a brief, 11-item questionnaire designed to be used in the primary care setting. The 11 symptoms used in the symptom checklist are based on 3 evidence-based criteria: 1.Symptoms fall into the six symptom domains that have been reported in the published literature. 2.The symptom reporting of the 11 symptoms in the major epidemiologic studies of Gulf War veterans met a threshold of 30%. 3.Symptoms were significantly higher in Gulf War deployed vs. Gulf Era non-deployed (either based on adjusted odds ratio and 95% confidence interval or prevalence rate difference and 95% confidence interval). The symptoms included in the checklist are joint pain, muscle pain, excessive fatigue, unrefreshing sleep, headache, difficulty concentrating/remembering, headache, diarrhea, stomach pain, shortness of breath/cough, sinus congestion/runny nose, and skin rash as well as severity measure for each symptom. These 11 symptoms included in the checklist include symptoms that were most frequently reported in the peer reviewed epidemiologic studies of GWI and in the VA’s Gulf War Registry and the DoD Comprehensive Clinical Evaluation Program. For a Veteran to meet the criteria for GWI using this 11-item questionnaire, a Veteran must report at least one symptom in at least three of the six symptom categories (pain, fatigue, neurocognitive, gastrointestinal, respiratory, and dermatological), and the symptoms must be rated as moderate or severe. The rationale for requiring at least one symptom from at least three different symptom categories is because the Gulf War illness literature has consistently demonstrated that the defining characteristic of this condition was a cluster of co-occurring symptoms, not just one or two symptoms.