Objectives: In infants less than 1 year of age, the value of endoscopic third ventriculostomy (ETV) is controversial. It is believed to cause more morbidity and to have higher failure rates. We analyzed our data enlarging the reported pool of ETV outcome in infants less than 1 year of age., Materials and Methods: We performed 12 ETVs in ten patients younger than 1 year of age. All patients had predominant supratentorial hydrocephalus. We defined ETV success as a shunt-free follow-up of at least 12 months, however, allowing re-ETV., Conclusion: ETV should be considered as initial treatment and carries low morbidity in these infants. As the immune system rapidly matures, postponing shunt implantation for several months or even weeks would make an ETV procedure worthwhile. On the other hand, as success probability rapidly increases 4 months after birth, re-ETV should always be considered first.