Introduction: Ischemic stroke in young adults can have a significant impact on the affected individuals by leaving victims disabled during their most productive years. While atherosclerosis, hypertension and diabetes mellitus are the most common risk factors among the elderly, the etiologies of ischemic stroke in young adults are different and mainly searching for an underlying thrombophilic state. Aim of the study: The aim of this study was to analyze patients with previous ischemic stroke and patent foramen ovale (PFO) and identify patients with thrombophilia or thrombophilic disorders that may be causal risk factors for a proportion of ischemic strokes. Methodology: We conducted a retrospective study at the University Hospital Center Zagreb and we included patients with ischemic stroke and PFO at an age of <65 at onset. We collected data on patients’ relevant clinical history – demographic data, thrombophilia screening and information on the diagnostic method used to confirm PFO. Results: In this study, we identified 57 patients aged <65 having ischemic stroke and PFO. The mean age was 44 (range 20 – 64). There was an overall female predominance (58%). Thrombophilia screening revealed 14 (25%) positive tests. FV Leiden mutation was detected in 7% of patients, prothrombin mutation in 5% of patients. Low values of protein S were identified in 9% of patients. Also, 3.5% of patients had high homocysteine levels and 3.5% of patients high levels of lipoprotein (a). 5% of patients were diagnosed having antiphospholipid syndrome. The most common finding was elevated FVIII in 26% of patients. Transesophageal echocardiography was performed in 80% of patients, and revealed PFO in 67% of patients. A functional right-left shunt was confirmed in all patients by agitated saline contrast study (“bubble „test), which also revealed right-left shunt in 14% of patients with normal findings on transesophageal echocardiography. Conclusion: In our study, thrombophilia was detected in 25% of patients with PFO who suffered an ischemic stroke at a younger age. The results indicate the need to test younger patients with PFO and ischemic stroke for hereditary thrombophilias, since their finding may change the therapeutic approach to prevent stroke recurrence.