Background: Endoscopic third ventriculostomy is increasingly used in the treatment of hydrocephalus. It is considered treatment of choice in obstructive hydrocephalus. There are varying opinions about results of ETV in infants. We therefore prospectively studied the outcome of endoscopic third ventriculostomy in infants with obstructive hydrocephalus. Aim: To investigate the outcome of endoscopic third ventriculostomy in infants with obstructive hydrocephalus. Methods & Materials: A prospective study of 34 infants undergoing ETV in our institution from July 2013 to December 2015 was carried out. Obstruction was revealed by preoperative computed tomographic scan and magnetic resonace imaging. The etiology of obstructive hydrocephalus was congenital aqueductal stenosis in twenty five patients, posthemorrhagic obstruction in two patients and postinfection etiology in seven patients. The results of ETV were determined by assessing clinical signs of raised intracranial pressure, head circumference measurements and fontanelle tension, as well as by MRI / CT scans and post operative CSF flow studies. ETV was considered successful if a patient showed clinical evidence of normal intracranial pressure and structural evidence of stable or decreased ventricular size whereas was considered failure in cases in which a patient showed no change in clinical symptoms or requires placement of a shunt within days or months of the procedure. Results: ETV was successful in 28 patients with a mean follow up period of 14.6 months. Successful procedure was noted in 88% patients with aqueductal stenosis, 50% with posthaemorrhagic and 71.4% with postinfective obstructive hydrocephalus. In 6 patients ETV was considered failure. These patients required a shunt. Out of 6 patients with failure, five of them were less than 6 months old when ETV was performed and four of them were low birth weight pre mature infants. Overall success rate was 82.3% in infants with obstructive hydrocephalus. Conclusion: ETV is a better alternative surgical treatment to shunt surgery for obstructive hydrocephalus in infants. Its fairly safe and effective. Posthaemorrhagic and Postinfective obstructive hydrocephalus have more failure rate as compared to congenital obstructive hydrocephalus due to aqueductal stenosis. Efficacy of ETV was better in full term normal birth weight infant as compared to low birth weight pre mature infants.