Although the cracked tooth syndrome has been known for over twenty years, it frequently remains undiagnosed because the condition is not sufficiently well recognized. Cracked tooth syndrome has been defined as an incomplete fracture of the dentine in a vital posterior tooth, and must be distinguished from a split tooth. A diagnosis can often be made by means of the history, and must be confirmed by reproducing the patient's symptoms. The ideal treatment consists of applying a stainless steel band to the tooth, with cessation of symptoms confirming the diagnosis, followed by a full coverage restoration. Case histories illustrating the syndrome are presented, and a further case is reported where a diagnosis of cracked tooth syndrome was made, and the tooth extracted, sectioned and stained to show the nature of the cracks and their relationship to the pulp.