Purpose: To determine if a very effective therapy for心opathic orthostatic cyclic edema - dextroamphetamine sulfate - would alleviate symptoms of chonic pelvic pain of bladder origin/interstitial cystitis. Methods: Two women with interstitial cystitis that had been refractory to various therapies were treated with dextroamphetamme sulfate (20 mg/day) without any other treatment. The diagnosis of idiopathic edema was made by abnormal water load test and interstitial cystitis diagnosed by elevated scores on the pelvic pain and urgency and frequency symptom scale. Results: Both patients quickly improved their bladder symptoms and all pain and urgency was gone within a week. The interstitial cystitis remained in remission as long as the women stayed on their medication. One woman proved Koch’s postulates by stopping the medication because of forgetting it and symptoms resumed quickly only to disappear again upon resuming therapy. Conclusions: Dextroamphetamine sulfate can be a very effective therapy for recalcitrant cases of interstitial cystitis. Prospective placebo controlled studies are needed to determine what percentage of patients with this debilitating condition have concomitant idiopathic edema as determined by abnormal water load test and how well a larger series will respond to this novel therapy.