Purpose: To show that chronic fatigue syndrome can be mistakenly attributed to Lyme disease rather than considering sympathetic neural hyperalgesia edema syndrome. This common disorder of women, frequently, but not always causing pelvic pain, can presentsimply as chronic fatigue. Methods: A water load test was performed in a woman reactive for B-Burgdorferi with chronic fatigue whose symptoms did not improve despite three months of treatment with doxycycline. A water load test was performed. Results: She failed the water load test by excreting only 50% ingested load standing for four hours. She showed marked improvement following treatment with dextroamphetamine sulfate. Conclusions: This very treatable disorder of the sympathetic nervous system should be considered in women with an unknown cause of chronic fatigue or if the symptoms persist despite treatment of another potential cause.