Summary: The Centers for Disease Control and Prevention (CDC) continues to work with the World Health Organization (WHO) and other partners to closely monitor Middle East Respiratory Syndrome Coronavirus (MERS-CoV) globally, including the cases of MERS-CoV infection recently reported by China and the Republic of Korea, to better understand the risks to public health. The purpose of this HAN Advisory is to provide updated guidance to state health departments and healthcare providers in the evaluation of patients for MERS-CoV infection, which have been revised in light of the current situation in the Republic of Korea. Healthcare providers and public health officials should maintain awareness of the need to consider MERS-CoV infection in ill persons who have recently traveled from countries in or near the Arabian Peninsula1 or in the Republic of Korea as outlined in the guidance below. Please disseminate this information to healthcare providers, especially infectious diseases specialists, intensive care physicians, internists, infection preventionists, and to emergency departments and microbiology laboratories.