All six World Health Organization (WHO) regions have established measles elimination goals, and three regions have a rubella elimination goal. Each region has established a regional verification commission to monitor progress toward measles elimination, rubella elimination, or both, and to provide verification of elimination* (1,2). To verify elimination, high-quality case-based surveillance is essential, including laboratory confirmation of suspected cases and genotyping of viruses from confirmed cases to track transmission pathways. In 2000, WHO established the Global Measles and Rubella Laboratory Network (GMRLN) to provide high-quality laboratory support for surveillance for measles, rubella, and congenital rubella syndrome (3). GMRLN is the largest globally coordinated laboratory network, with 704 laboratories supporting surveillance in 191 countries (4). This report updates a previous report and describes the genetic characterization of measles and rubella viruses during 2016-2018 (5). The genetic diversity of measles viruses (MeVs) and rubella viruses (RuVs) has decreased globally following implementation of measles and rubella elimination strategies. Among 10,857 MeV sequences reported to the global Measles Nucleotide Surveillance (MeaNS) database during 2016-2018, the number of MeV genotypes detected in ongoing transmission decreased from six in 2016 to four in 2018. Among the 1,296 RuV sequences submitted to the global Rubella Nucleotide Surveillance (RubeNS) database during the same period, the number of RuV genotypes detected decreased from five in 2016 to two in 2018. To strengthen laboratory surveillance for measles and rubella elimination, specimens should be collected from all confirmed cases for genotyping, and sequences from all wild-type measles and rubella viruses should be submitted to MeaNS and RubeNS in a timely manner.