['Chronic fatigue syndrome (CFS) has an uncertain pathogenesis. Allergies have been suggested as one cause.', 'The aim of this study was to compare serum immunoglobulin (Ig)E in CFS and control subjects to determine whether IgE levels were elevated in CFS. This would be suggestive of increased atopy in CFS.', 'IgE was measured by quantitative ELISA (sandwich) immunoassay in 95 CFS and 109 non-CFS control subjects. Subjects were classified by positive or negative allergy skin tests (AST) and rhinitis questionnaires (rhinitis score, RhSc) into four rhinitis types: nonallergic rhinitis (NAR with positive RhSc and negative AST); allergic rhinitis (AR with positive AST and RhSc); atopic/no rhinitis (AST positive/RhSc negative); and nonatopic/no rhinitis (both AST and RhSc negative) subjects.', 'IgE was not significantly different between control (128 +/- 18 IU/mL, mean +/- SEM) and CFS (133 +/- 43 IU/mL) groups, or between control and CFS groups classified into the four rhinitis types. IgE was significantly higher in subjects with positive AST whether or not they had positive RhSc or CFS symptoms.'] Are igE levels the same in chronic fatigue syndrome ( CFS ) and control subjects when stratified by allergy skin test results and rhinitis types?