Purpose Interstitial cystitis is a chronic debilitating condition that mainly affects women. Accumulated evidence indicates that interstitial cystitis is a heterogeneous syndrome. The nonulcer type seems to respond less favorably to various conservative treatments than the classic type. Supratrigonal cystectomy with ileocystoplasty is established treatment for interstitial cystitis refractory to conservative treatment. We evaluate whether classic interstitial cystitis responds differently than nonulcer disease to subtotal bladder resection and ileocystoplasty. Materials and Methods We evaluated 13 patients 27 to 79 years old with interstitial cystitis who underwent supratrigonal cystectomy and ileocystoplasty due to failure to respond to conservative treatment. Results In all 10 patients with classic interstitial cystitis symptoms were relieved after ileocystoplasty. In the 3 patients with nonulcer interstitial cystitis pain remained, while the frequency of voiding somewhat decreased. In these patients trigonal resection and urinary diversion with a Kock pouch resolved the symptoms. Conclusions Our study confirms that supratrigonal cystectomy with ileocystoplasty results in a good outcome in classic interstitial cystitis. However, this method seems to be unsuitable for nonulcer disease. Identification of the relevant subtype of interstitial cystitis is of crucial importance for selecting the appropriate method of lower urinary tract reconstruction.