Introduction and objective: Major bleeding events in patients undergoing left atrial appendage closure (LAAC) range from 2.2 to 10.3 per 100 patient-years in different series. This study aimed to clarify the bleeding predictive factors that could influence these differences. Methods: LAAC was performed in 598 patients from the Iberian Registry II (1093 patient-years; median, 75.4 years). We conducted a multivariate analysis to identify predictive risk factors for major bleeding events. The occurrence of thromboembolic and bleeding events was compared to rates expected from CHA2DS2-VASc (congestive heart failure, hypertension, age, diabetes, stroke history, vascular disease, sex) and HAS-BLED (hypertension, abnormal renal and liver function, stroke, bleeding, labile INR, elderly, drugs or alcohol) scores. Results: Cox regression analysis revealed that age ≥75 years (HR: 2.5; 95% CI: 1.3 to 4.8; p = 0.004) and a history of gastrointestinal bleeding (GIB) (HR: 2.1; 95% CI: 1.1 to 3.9; p = 0.020) were two factors independently associated with major bleeding during follow-up. Patients aged <75 or ≥75 years had median CHA2DS2-VASc scores of 4 (IQR: 2) and 5 (IQR: 2), respectively (p < 0.001) and HAS-BLED scores were 3 (IQR: 1) and 3 (IQR: 1) for each group (p = 0.007). Events presented as follow-up adjusted rates according to age groups were stroke (1.2% vs. 2.9%; HR: 2.4, p = 0.12) and major bleeding (3.7 vs. 9.0 per 100 patient-years; HR: 2.4, p = 0.002). Expected major bleedings according to HAS-BLED scores were 6.2% vs. 6.6%, respectively. In patients with GIB history, major bleeding events were 6.1% patient-years (HAS-BLED score was 3.8 ± 1.1) compared to 2.7% patients-year in patients with no previous GIB history (HAS-BLED score was 3.4 ± 1.2; p = 0.029). Conclusions: In this high-risk population, GIB history and age ≥75 years are the main predictors of major bleeding events after LAAC, especially during the first year. Age seems to have a greater influence on major bleeding events than on thromboembolic risk in these patients.