The purpose of the present study was to discern a symptom pattern for environmentally ill patients and provide evidence of the uniqueness of the resultant pattern to this population. Patients' environmental exposure was confirmed by the presence of toxins in the blood serum. All patients were administered psychological and physical symptom checklists, the Clinical Analysis Questionnaire, and a standardized intermediate neuropsychological examination. Results indicate a response pattern of symptoms including fatigue, low energy, weakness, poor concentration, poor memory, poor comprehension, headaches, aches and pains, clumsiness, sinus discomfort, mucus, eye problems, restlessness, and present performance inferior to prior level of functioning. Presence of these symptoms, as well as the uniqueness of this symptom pattern was supported by comparisons of the patient and standardization groups on the two standardized tests.