Hormone replacement therapy (HRT) is associated with risk of vascular disease. The association between atrial fibrillation (AF), vascular events, and different HRTs, including estradiol and conjugated equine estrogens (CEE), has been controversial in previous studies. Thus, we conducted a retrospective cohort study to investigate these associations. Female patients (>45 years old) first diagnosed with menopause were enrolled from National Health Insurance Research Dataset (1998-2008). Cox regression analysis estimated risk of new-onset AF, stroke, and major adverse cardiac events (MACE) after exposure to estradiol or CEE. Of 5489 females (mean age = 55 years) enrolled, 1815 treated with estradiol and 3674 treated with CEE. Incidence per 10(3) person-years of AF, stroke, and MACE in CEE vs estradiol patients was 2.23 vs. 0.92, 14.0 vs. 9.09, and 15.55 vs. 10.47. As compared with patients treated with estradiol, those treated with CEE had a significantly higher incidence of AF, stroke, and MACE. The adjusted hazard ratios for each category were 1.96, 1.30, and 1.26, respectively. The significant results remained similar, even after use of propensity-score-matched strategy. In conclusion, CEE was associated with a higher risk of AF, stroke, and MACE than estradiol in menopausal females. Further exploration of underlying mechanisms is necessary.