Surgical therapy of interstitial cystitis must never be considered a first option but must be reserved for cases, less than 10%, in which conservative therapy has proven ineffectual. Surgical therapy includes a variety that started at the turn of the century. Neurosurgical denervation and perivesical denervation like cysto-cystoplasty and cystolysis, manipulate the innervation to reduce the bladder's hypersensitivity. This surgical approach may be considered in patients in whom bladder capacity is normal. The results are uncertain and the complications like neurogenic bladder relevant. Enterocystoplasty is much more widespread because interstitial cystitis is a benign disease that rarely required radical surgery. Augmentation cystoplasty and substitution cystoplasty are two variants but only the later has a rationale as it involves the resection of the detrusor which is the source of the pain. Detubularization drastically reduced urinary incontinence. The resection of the detrusor can be supratrigonal, subtrigonal or at the proximal urethra like in the orthotopic neobladder. If urinary diversion is chosen, the bladder must be removed. Before recommending surgical therapy each patient should undergo tests for the localization of the pain; moreover psychological and gynaecological evaluations should be made. If the bladder capacity exceeds 400 cc surgical operation is not advisable. If, on the other hand, the bladder capacity is lower than 400 cc substitution cystoplasty is first choice. If the patient suffers from trigonal cystitis or urethral hypersensitivity, urinary diversion is a better therapy. According to the questionnaires send to the Urologic Departments in Lombardy in 1998, the most widespread type of operation seems to be supratrigonal cystectomy + enterocystoplasty and augmentation cystoplasty. Subtrigonal cystectomy or urinary diversion are only occasionally chosen; continent pouch is the least frequent therapy at all.