A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether the optimal treatment strategy for acute prosthetic valve thrombosis (PVT) is surgical management or thrombolytic therapy. Using the reported search 96 papers were identified. Twelve papers represented the best evidence on the subject, and the author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study comments and weaknesses were tabulated for these. Recent AHA/ACC guidelines were also included, as were two large case series of surgical management for comparison. We conclude that the management of obstructive PVT remains widely debated due to a lack of randomised controlled trials. Surgery has been the traditional management of choice, but thrombolysis has recently been proposed as a first-line therapy. Both surgery and thrombolysis can be used with high rates of success and relatively low complication rates, though NYHA class at presentation has a significant bearing on surgical mortality and thrombus size affects complication rates with thrombolysis. Thrombolysis appears particularly favoured when the thrombus area as assessed by transoesophageal echocardiography is small (<0.8 cm(2)), as high success rates and low complication rates have been reported, and thrombolysis does not preclude the patient from proceeding to surgery if it fails. Presentation in a high NYHA class of heart failure or cardiogenic shock is the most difficult patient to decide between surgery and thrombolysis. Surgery for these patients may remain the mainstay of treatment unless the clot burden is particularly small or the patient's co-morbidities make surgery unacceptably high-risk.