The aim of this study was to evaluate the risk of recurrent ischaemic cerebrovascular events (stroke or transient ischaemic attack (TIA)) in patients with patent foramen ovale (PFO) or atrial septal aneurysm (ASA) treated with different therapeutic regimens. We enrolled 86 patients aged 18-60 years with an unexplained ischaemic stroke or TIA referred to our inpatient department in the period May 1994-December 1999. Follow-up lasted until April 2003. Patients were excluded if the stroke or TIA was related to large-artery atherosclerosis, small artery occlusion, major cardiac sources of embolism or other uncommon causes. During a follow-up (mean+/-SD) of 64.1+/-28.8 months (range 8.1-105.6) a recurrent ischaemic cerebrovascular event occurred in 11/86 patients (12.8%) (5 TIA and 6 strokes). Eight events (4 TIA, 4 strokes) occurred in the 59 patients with PFO alone, three (1 TIA, 2 strokes) in the 21 with PFO plus ASA and none in the 6 patients with ASA alone. In the overall population the cumulative risk of recurrent stroke/TIA was 1.2% at 2 years, 5.5% at 4 years, 7.6% at 6 years and 23.6% at 8 years, and was similar in patients with PFO alone vs. patients with PFO plus ASA (9.0% vs. 6.1% at 6 years, 26.0% vs. 23.1% at 8 years; p>0.05). Nine cerebral ischaemic events (4 TIA, 5 strokes) occurred in the 48 patients treated with antiplatelet drugs (7 in patients with PFO, 2 in patients with PFO plus ASA), and two (1 TIA, 1 stroke) in the 17 patients treated with oral anticoagulants (1 with PFO, 1 with PFO plus ASA). No events occurred in patients submitted to transcatheteral closure.