The epidemic of microcephaly in Brazil has been declared a Public Health Emergency of International Concern by WHO.1 The declaration states that a causal relationship between Zika virus infection during pregnancy and microcephaly is strongly suspected, although not yet scientifically proven.1 The hesitancy to accept causation in the presence of much epidemiological circumstantial evidence is due to the paucity of laboratory confirmation of Zika virus in affected neonates. Here, we report the serological confirmation of Zika virus infection in the CNS of 30 neonates with microcephaly.