Current methodology permits one to define the functional basis of the preexcitation syndromes with reasonable certainty and to develop a rationale for instituting trials of medical therapy. Future studies will hopefully result in a more exact definition of the anatomic substrates of preexcitation and their relationship to the pathophysiology of the associated syndromes. New antiarrhythmic agents must also be developed to add to the relatively small number of available drugs. Important questions still remain. Should asymptomatic patients with preexcitation be studied? If found to demonstrate potential for malignant arrhythmias, should they be treated prophylactically? The answers to these questions will require study and long-term follow-up of nonhospital referral patients. Surgery offers a feasible therapeutic alternative for patients with life-threatening or disabling arrhythmias but demands a team equipped to perform precise preoperative and intraoperative mapping studies to define the type and location of underlying anatomic substrates.