To examine the association between patent foramen ovale (PFO) and atrial septal aneurysm (ASA) and stroke. Data from case-control studies that examined the relative frequency of PFO, ASA, or both, in all patients with ischemic stroke, cryptogenic stroke, and known stroke cause as well as control subjects were included. Trials were categorized by age, clinical comparison, and abnormality. Combined OR were calculated using fixed effect (FE) and random effect (RE) methods. Comparing patients with ischemic stroke with control subjects using RE, OR for all ages was 1.83 (95% CI, 1.25 to 2.66) for PFO (15 studies), 2.35 (95% CI, 1.46 to 3.77) for ASA (nine studies), and 4.96 (95% CI, 2.37 to 10.39) for PFO plus ASA (four studies). Homogeneous results were found within the group younger than age 55: using FE, OR was 3.10 (95% CI, 2.29 to 4.21) for PFO, 6.14 (95% CI, 2.47 to 15.22) for ASA, and 15.59 (95% CI, 2.83 to 85.87) for PFO plus ASA. For patients older than age 55, using FE, OR was 1.27 (95% CI, 0.80 to 2.01) for PFO, 3.43 (95% CI, 1.89 to 6.22) for ASA, and 5.09 (95% CI, 1.25 to 20.74) for PFO plus ASA. Comparing cryptogenic stroke with known stroke cause, heterogeneous results were derived from total group examination using RE: OR was 3.16 (95% CI, 2.30 to 4.35) for PFO (22 studies), 3.65 (95% CI, 1.34 to 9.97) for ASA (five studies), and 23.26 (95% CI, 5.24 to 103.20) for PFO plus ASA (two studies). In patients younger than age 55, using FE the OR was 6.00 (95% CI, 3.72 to 9.68) for PFO; only one study examined ASA or PFO plus ASA. In patients aged 55 years or older, three studies produced heterogeneous results for PFO: using RE, OR was 2.26 (95% CI, 0.96 to 5.31); no data were available on ASA prevalence. PFO and ASA are significantly associated with ischemic stroke in patients younger than 55 years. Further studies are needed to establish whether an association exists between PFO and ischemic stroke in those older than 55.