Interstitial cystitis (IC) is characterized by pain in the region of the bladder and pelvic musculature, and variable motor and sensory dysfunctions of the bladder. The most prevalent symptoms of IC are urinary frequency, urgency and suprapubic, perineal pain. IC can be classified into the two categories of Hunner's ulcer and nonulcer, based on cystoscopic findings. This chapter highlights research contradictions regarding IC, along with research findings relating to the therapeutic effectiveness of various treatment modalities in IC. The lack of specific pathognomonic markers for the diagnosis of IC has resulted in a host of plausible hypotheses for its etiology. To be diagnosed with IC, patients must undergo cystoscopic examination under general anesthesia with hydrodistention of the bladder and bladder biopsy. Antihistamines are critical to managing IC in people with hay fever, sinusitis or food allergies. One major breakthrough in therapy is the use of heparin-like drugs.