Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by arterial and/or venous thromboses and/or pregnancy-associated morbidity. Some patients develop only obstetric complications (obstetric APS), but data on the frequency of thrombotic events during the follow-up of these patients are scarce. This study was undertaken to evaluate the rate of thrombotic events after obstetric APS diagnosis according to the 2006 revised criteria. In total, 32 obstetric APS patients were retrospectively studied, with mean follow-up of 50 ± 37 months. After delivery, aspirin was prescribed to all patients as primary thrombosis prevention. The thrombosis rate was 3.3/100 patient-years and was 4.6, 4.5 and 10/100 patient-years when we considered at least two antiphospholipid antibody positivities (among lupus anticoagulant, anticardiolipin and anti-β2-glycoprotein-I), antinuclear antibody positivity or systemic lupus erythematosus-associated APS patients, respectively. The thrombosis rate was high after obstetric APS diagnosis, even for patients taking aspirin. Larger, prospective studies are needed to confirm this high frequency and determine the associated risk factors.