The present disclosure provides methods and compositions that find use in facilitating a diagnosis of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) in a subject. The methods and compositions involve measurement of at least one of proteins: IL-16, IL-7, VEGF, CXCL9, CX3CL1, CCL24, CCL19, and CCL11 in a body fluid sample of a subject suspected of having CFS/ME. Levels of one or more of the aforementioned proteins can be used to facilitate a diagnosis of a CFS/ME and/or confirm a diagnosis of CFS/ME. The methods and compositions of the present disclosure also find use in screening subjects for clinical trials and facilitating treatment decisions for a subject.