Abstract Background Atrial fibrillation (AF) is the most common arrhythmia in adults and is associated with an increased risk of embolic stroke. In a previous survey, 91% of nonrheumatic AF-related left atrial thrombi was originated in the left atrial appendage (LAA). Percutaneous left atrial appendage closure (LAAC) with the Watchman device has been shown to be noninferior to anticoagulation therapy in clinical trials for stroke prevention in nonrheumatic AF. It has been used in Japan since September 2019 only for patients who are at the high risk of bleeding events. The WATCHMAN family is the only left atrial appendage closure (LAAC) device in Japan. Since long time ago, sex differences have been attracting attention in the cardiology. Due to the cardiovascular protective effects of endogenous estrogens, premenopausal women are thought to be less likely to develop cardiovascular disease. Whereas, in area of AF, Female with AF have higher stroke risk and female with AF have severe after effect. However, there are few studies on sex differences in LAAC implantation outcomes. Purpose We aimed to identify the sex differences of outcomes of LAAC in Japanese patients. Methods A total of 118 consecutive patients who underwent LAAC at our hospital from January 2020 to August 2023 were prospectively analyzed. Various patient characteristics, comorbidities, and outcomes were identified and compared between male and female. Results Results are shown in Table. Female were older (79 vs. 73 years, p = 0.0009), thinner (Body mass index 22 vs. 24 kg/m2, p = 0.0326), and less likely to have had diabetes (19 vs. 40%, p = 0.0340). Pulmonary embolism was significantly more common in female after LAAC. If anticoagulants are discontinued after LAAC, women’s susceptibility to coagulation may become apparent. Conclusions LAAC was feasible and safe for Japanese patients of both genders. However, these results could have a relevant impact on the antithrombotic management of patients who are at the high risk of embolic considering sex difference. Especially, we should pay great attention when discontinuing anticoagulants after LAAC in female.