Objectives: To investigate trends in cardiovascular disease (CVD) risk following breast cancer using national registry data. Methods: A nationwide cohort study was conducted, comprising 163 881 women with in situ (7.6%) or invasive (92.4%) breast cancer and women of the general population, ranging from 3 661 141 in 1996 to 4 566 573 in 2010. CVD mortality rate in women with and without breast cancer and hospitalisation rate after breast cancer were calculated for the years 1996-2010. Age-adjusted CVD and breast cancer mortality within 5 years after breast cancer admission (1997-2010) were compared with 1996 calculated with a Cox proportional hazard analysis. Results: The absolute 10-year CVD mortality risk following breast cancer decreased from 56 per 1000 women in 1996 to 41 in 2005 (relative reduction=27.8%). In the general population, this decreased from 73 per 1000 women in 1996 to 55 in 2005 (-23.9%). The absolute risk of CVD hospitalisation within 1 year following breast cancer increased from 54 per 1000 women in 1996 to 67 in 2009 (+23.6%), which was largely explained by an increase in hospitalisation for hypertension, pulmonary embolism, rheumatoid heart/valve disease and heart failure. The 5-year CVD mortality risk was 42% lower (HR 0.58, 95% CI=0.48 to 0.70) for women admitted for breast cancer in 2010 compared with 1996. Conclusions: CVD mortality risk decreased in women with breast cancer and in women of the general population, with women with breast cancer having a lower risk of CVD mortality. By contrast, there was an increase in hospitalisation for CVD in women with breast cancer.