Until recently, interstitial cystitis (IC) was considered a urologic curiosity, a rare problem that most urologists would see only a few times during a career. It was easy to diagnose, with strict and rigid criteria having been set early in this century [28]. This situation has changed drastically in the last 15 years, largely as a result of patients themselves, who have banded together in large, well-organized lobbying and self-help groups throughout North America. The medical catalyst for the change came from a paper published in 1978 by Messing and Stamey [39], who proposed that previous diagnostic criteria for the disease were too limited. IC is now a very controversial subject that has ignited the interest of physicians in many nations and has sparked a major basic scientific research effort to discern its etiology and discover potential treatment modalities. The major effort in the last 5 years has been devoted to the attempt to define the disorder. In this article we review the current status of interstitial cystitis with regard to issues of definition, epidemiology, diagnosis, and treatment. Finally, current avenues of research are discussed.