Ideally, for the decision about the duration of vitamin K antagonists as secondary prophylaxis after an episode of venous thromboembolism, knowledge about at least three aspects is needed. First, the chance of a recurrence of venous thromboembolism, second, the risk of major bleeding complications, and third, the patient’s appreciation of being on or off warfarin. At present, the lack of solid data for most of these elements leaves the clinician with many uncertainties.