Abstract: Objective: To explore the associations of adult leukemia and its different subtypes with the new-onset cardiovascular diseases(CVD) using the large-scale cohort of the UK Biobank(UKB). Methods: A retrospective cohort analysis was carried out on the prospective UKB database. One-to-five propensity score matching was used to match the leukemia-exposed group(n=1, 269) with the unexposed group(n=6, 241) based on demographic, lifestyle, and clinical baseline covariates. The median follow-up duration of the cohort was 15.41 years(14.42-16.20 years). Multivariable Cox regression was used to estimate the hazard ratios(HRs) and 95% confidence intervals(CIs) for the new-onset risk of CVD, including atrial fibrillation or atrial flutter, conduction system disease, ischaemic heart disease, heart failure or cardiomyopathy, valvular heart disease, peripheral arterial disease, myocarditis or pericarditis, and stroke. Results: Leukemia diagnosis was associated with an increased risk of most assessed CVD outcomes, with myocarditis or pericarditis showing the greatest increase in risk(HR=5.21, 95% CI: 3.24 - 8.40, P<0.001). The risks of other CVD outcomes also showed varying degrees of increased risk: the HRs for heart failure or cardiomyopathy, valvular heart disease, stroke, and atrial fibrillation or atrial flutter were 3.28, 3.03, 2.63 and 2.11, respectively(P<0.001). In subtype-stratified analyses, the risks of heart failure or cardiomyopathy and myocarditis or pericarditis were higher in patients with myeloid leukemia than in those with lymphoid leukemia. Conclusion: Adult leukemia is significantly associated with an increased risk of multiple new-onset CVD outcomes, most notably myocarditis or pericarditis and heart failure or cardiomyopathy, particularly in patients with myeloid leukemia.