Abstract Background Transcatheter device closure is the preferred therapeutic option for ostium secundum atrial septal defect(OS-ASD). Standard practice is to perform it under transoesophageal echocardiography(TEE) guidance. However, TEE is performed under general anaesthesia (GA) and leads to increases in cost, procedural duration, ICU stay, total hospital stays, risk of oesophageal injury and complications of GA. Transthoracic echocardiography(TTE) is an excellent alternative and prior studies have shown it to be a safe alternative in paediatric population. In current study we analysed safety and efficacy of TTE-guided device closure of OS-ASD in all comer population irrespective of age, weight, defect size. Methods The study enrolled all patients who underwent device closure of OS-ASD between March 2017 and December 2023. All procedures were performed under LA for adults and conscious sedation for children. The device was placed under fluoroscopy guidance and position were confirmed on TTE. Procedural success, device, defect size ratio, procedural time, fluoroscopy time, complications, intensive care unit/hospital stay duration were analysed and compared with our own experience of 125 patients with TEE-guided closures before switching to complete TTE-guided procedure(before 2017). Results 340 patients underwent TTE-guided device closure of ASD. Procedure success was 97.4% with acceptable risk of major complications. Three(0.8%) had embolization into pulmonary artery, successfully operated surgically. Two had tamponade requiring drainage. In 9 patients, device could not be deployed despite multiple attempts and approaches. All of these had defect size of > 34mm and deficient IVC rim along with shorter (other than aortic) rim. Findings were compared with our own previous experience of TOE guided closure (practised before 2017). Compared to TOE group, TTE group had significantly lower total procedural duration (75±4 vs. 28 ±1 min; p < 0.01), intensive care unit stay (24±10 vs. 10.5±1 h; p < 0.01), and hospital (48±12 vs. 25.5±4h; p < 0.01) stay duration. Fluoroscopic time was similar in both. There was no mortality in either group. Major complications were comparable, TTE-guided group had less post-procedure complications of vomiting and headache. Additional findings of less pre-procedure fasting duration and early commencement of post procedure oral intake were noted in TTE group. Conclusion TTE-guided device closure of OS-ASD is a safe and feasible in all-comer population in experienced hands. It can definitely negate the use of TEE except in very poor echo window. The added advantages include utilization of physiological variations in PV/LV pressure during cough, Valsalva manoeuvres in awake patients. It definitely reduces the procedural duration, cost of procedure and dependence on GA and trained transoesophageal echocardiographer.