Interstitial cystitis is an enigmatic and frustrating condition to manage as a physician and to cope with as a patient. Traditionally, it has been defined as a chronic sterile inflammatory disease of the bladder of unknown aetiology. However, the International Continence Society prefers the term painful bladder syndrome and it has been decided to follow this terminology and refer to the disease as painful bladder syndrome/interstitial cystitis (PBS/IC). The condition is characterized by bladder pain, urinary frequency, urgency and nocturia. The quality of life of patients with PBS/IC is significantly degraded. Its aetiology is unknown, but might involve microbiologic, immunologic, mucosal, neurogenic and other yet unidentified agents. History, physical examination, urine analysis and culture as well as cystoscopy and hydrodistension are useful diagnostic tools but the final diagnosis tends to be a diagnosis of exclusion. This article will review the major theories of aetiology for PBS/IC and discuss diagnosis as well as the current treatment options with relevance to the proposed aetiologies.