In early 2015, a Zika virus outbreak was identified in northeast Brazil, coinciding with an increase in reports of microcephaly in infants born to mothers who had lived in or visited Zika-affected areas. The Brazilian Ministry of Health (MoH) established a task force and registry to investigate the possible association between Zika virus infection during pregnancy and microcephaly. Among the first 35 cases reported, 74% of mothers reported a rash during pregnancy, 71% of infants had severe microcephaly, and approximately half had at least one neurological abnormality. All infants tested negative for other congenital infections. Cerebrospinal fluid samples from all infants are being tested for Zika virus, but results are not yet available. The findings suggest a possible relationship between Zika virus infection and microcephaly, and further studies are needed to confirm this association and understand other adverse pregnancy outcomes. Pregnant women in Zika-affected areas should take preventive measures to avoid mosquito bites.In early 2015, a Zika virus outbreak was identified in northeast Brazil, coinciding with an increase in reports of microcephaly in infants born to mothers who had lived in or visited Zika-affected areas. The Brazilian Ministry of Health (MoH) established a task force and registry to investigate the possible association between Zika virus infection during pregnancy and microcephaly. Among the first 35 cases reported, 74% of mothers reported a rash during pregnancy, 71% of infants had severe microcephaly, and approximately half had at least one neurological abnormality. All infants tested negative for other congenital infections. Cerebrospinal fluid samples from all infants are being tested for Zika virus, but results are not yet available. The findings suggest a possible relationship between Zika virus infection and microcephaly, and further studies are needed to confirm this association and understand other adverse pregnancy outcomes. Pregnant women in Zika-affected areas should take preventive measures to avoid mosquito bites.