OBJECTIVES: To assess the use of platelet aggregation inhibitors in patients who were hospitalised for ischemic events between 1998 and 2002. METHODS: Data were obtained from the PHARMO database, which includes linked drug-dispensing records and hospital records of more than 865,000 subjects in defined areas in the Netherlands. All patients hospitalised between 1998 and 2002 for ischemic heart disease (IHD), cerebrovascular disease (CVD), peripheral arterial disease (PAD) or having a percutaneous transluminal coronary angioplasty (PTCA), were included in this retrospective population based cohort study. The main outcome was the percentage of patients using different types of platelet aggregation inhibitors specified per indication within one month after discharge. RESULTS: In total, 18,646 patients were included in this cohort. In 2002, 66% of all patients with IHD, 61% of patients with CVD and 33% of patients with PAD were treated with platelet inhibitors. More than 80% of all patients with a first admission for an acute myocardial infarction or PTCA in 2002 were treated with platelet aggregation inhibitors. Clopidogrel use (including combined with aspirin) was most common in patients with IHD (15% of all patients in 2002) and limited in patients with CVD (5%) or PAD (2%). Clopidogrel (mainly in 2002) was almost only combined with ASA in patients with IHD (11% of all patients), especially in patients after PTCA (29%). CONCLUSIONS: There is still a considerable proportion of patients who do not use antiplatelet therapy after ischemic events. Clopidogrel use for secondary prevention in patients with ischemic vascular diseases seems to be rational given that guidelines recommend it for patients who can not be treated with aspirin. Clopidogrel plus aspirin is mostly used in patients with IHD treated with PTCA, suggesting that the current guidelines recommending this combination therapy in patients with acute coronary syndrome and after PTCA, are increasingly applied.