This document provides guidelines for the design and implementation of actions for the surveillance of microcephaly and other associated conditions. These guidelines are for health care workers responsible for the implementation of public health surveillance at the ministries of health in the countries, promoting harmonized criteria for operations and strategies. Although this document focuses specifically on microcephaly, it is part of a broader initiative for the surveillance of congenital defects in the Region, given the burden of morbidity and mortality they represent (congenital malformations are the second leading cause of child mortality in the Region of the Americas). This process is geared to strengthening the identification of congenital defects in the planning and implementation of public health actions, including surveillance. These preliminary recommendations were prepared by the PAHO/WHO team, with expert advice and based on currently available data and evidence. This document may be revised and updated in the light of new evidence that may become available.