Background:.Hydrocephalus in infancy is usually treated with a ventriculo-peritoneal (VP) shunt, however, endoscopic third ventriculostomy (ETV) is a successful procedure of treatment for obstructive hydrocephalus. Aim of the Work: to analyze the outcome of ETV as a treatment for hydrocephalus in infants aged less than 1 year. Patients and Methods: : An analytical prospective study conducted on 40 obstructive hydrocephalus in infants younger than one year of age treated via ETV approach in Al Azhar university hospitals in the period September 2017 to September 2020. Follow up of patients done clinically and radiologically over 6 months. Results: The study included 40 patients, 24 (60%) males and 16 (40%) females, with mean age of the included cases was 7.73 months (range, 2-12 months). Success was achieved in 22 cases (55%), while failure was encountered in the remaining ones (45%). Conclusion: Our study confirmed that ETV is a simple, minimally invasive procedure in general gives a good clinical and radiological outcome, ETV should be the first line in the bstructive hydrocephalus treatment in pediatric patients blow one year of age.