Background and Objectives: Surgical closure of ASD in patients below 30 years of age thought to improves the outcome. Aim of this study was evaluation of the surgical repair of ASD in adult age groups as regarding the preoperative, operative and post-operative factors that affect mortality, morbidities and assessment of clinical and radiological improvement signs Methods: From December 2011 to August 2013, our prospective randomized comparative study was conducted between adult patients with ASD with short term follow up (6 months). The study population were 40 patients classified as (group I); 20 patients at or above the age of 30 years, (group II); 20 patients below the age of 30 years. In both groups surgical closure were done. The main variables analyzed pre and post operatively were the NYHA class, ECG rhythm, ventricular functions, right sided dimensions, systolic pulmonary artery pressure, the degree of tricuspid regurgitation. Main operative variables included were the approach and type of surgical closure, cardioplegia time, ischaemic time with the ICU and hospital stay periods.Results: We found that ASD cases in whom surgical closure of their defect were done below 30 years (group II) showed significant improvement after 6 months regarding of NYHA grades(P =0.02),more PASP reduction (P =0.003)and significant improvement of left sided contractility (P =0.010)with less ICU stay period (P =0.044) as compared with (group I). In group I there was higher preoperative incidence of AF (p =0.02), advanced NYHA classes (p =0.043), higher PASP (P =0.009) and lower EF ((P =0.008). There was no statistically significant difference between groups regarding the other variables. Conclusions: Surgical closure of ASD in patients below 30 years of age improves patient symptoms, allows more PASP reduction and faster left ventricular recovery and the risk increases with older ages at the time of closure therefore early closure is strongly recommended.