Acute respiratory distress syndrome (ARDS) is a syndrome of acute respiratory failure that is associated with several clinical disorders including direct pulmonary injury and indirect pulmonary injury. Vascular surgical patients are at risk for ARDS. A 23-year old man was admitted to our respiratory intensive care unit with short of breath, cyanosis and agitation which was developed acutely after varicocele operation under epidural anesthesia lasted for one hour. Bupivacain, fentanyl, remifentadyl and midazolam were used for epidural anesthesia. Oxygen saturation was 81% while breathing oxygen at FiO(2) of 0.5. Arterial blood gas analysis showed hypoxemia with respiratory alkalosis with a PaO(2)/FiO(2) score of 100. A chest radiograph demonstrated bilateral alveolar opacities. Bedside echocardiography was performed which revealed no evidence of global hypokinesia, all the chambers were normal, left ventricular ejection fraction was 65%. A diagnosis of ARDS was made and the patient was initiated on noninvasive mechanical ventilation. He was gradually weaned off the NIMV and discharged after a total hospital stay of four days. We report an ARDS case due to unexplained etiology after varicocele operation under epidural anesthesia and managed successfully with noninvasive mechanical ventilation.