PURPOSE: To assess the incidence of cardiovascular events among breast cancer patients after chemotherapy. METHODS: Women >/=18 years with a breast tumour who received chemotherapy in 1992-2003 were selected from the PHARMO RLS. Chemotherapy with athracyclines, a combination of anthracyclines and taxanes or second line treatment with trastuzumab was classified as cardiotoxic. Cardiovascular events were determined based on drug use and hospital admissions. Incidence rates of cardiovascular events and hazard ratios (HR) for the cardiotoxic versus non-cardiotoxic chemotherapy group were assessed during the first year and total follow-up. RESULTS: Of 648 patients with breast cancer included in the study cohort, 353 (54%) received cardiotoxic chemotherapy. At baseline, patients who received cardiotoxic chemotherapy compared with patients receiving non-cardiotoxic chemotherapy, received less anticoagulants/haemostatics (5 vs. 11%; p = 0.012) and had been less often hospitalised for cardiovascular disease (1 vs. 5%; p = 0.007) 2 years before the cohort entry date. After 1-year follow-up, the incidence rate of cardiovascular events was 69/1000 person years (py) for patients with cardiotoxic chemotherapy and 98/1000 py for patients with non-cardiotoxicchemotherapy, which did not differ significantly (HR 0.74 95% confidence interval (CI): 0.39, 1.41). After total follow-up, this was 81/1000 py for patients with cardiotoxic and 92/1000 py for patients with non-cardiotoxic chemotherapy (HR 0.81, 95%CI: 0.54, 1.20). CONCLUSIONS: This study showed similar cardiovascular incidence rates during follow-up for breast cancer patients treated with cardiotoxic and non-cardiotoxic chemotherapy. Specialists seemed to take pre-existing cardiovascular diseases intoaccount when treating the breast cancer patient. Copyright (c) 2007 John Wiley & Sons, Ltd.