Taxol is one of the more significant advances in cancer chemotherapy in the last 10-15 years with a 30-50% response rate in both breast and ovarian cancers. The toxicity profile of taxol is still evolving as changes in the dosing and scheduling of the drug are instituted. We herein present the first evidence of taxol-induced quantifiable, objective autonomic neuropathy in two patients, one with and one without diabetes. The patients did not have symptoms of autonomic dysfunction prior to taxol therapy. Both developed severe orthostatic hypotension following completion of 24-hr infusional taxol at 170-250 mg/m2 and both improved markedly on fludrocortisone. Other possible etiologies of orthostatic hypotension were ruled out. Noninvasive autonomic tests performed on the first patient included tilt test, Valsalva ratio, heart rate variation with respiration, and change in diastolic blood pressure with hand grip; all were markedly abnormal. Noninvasive autonomic tests should be considered as part of the evaluation of patients on taxol who develop generalized weakness and orthostasis.