CIU

CIU may refer to:
 * Crash Investigation Unit, an Australian factual television program
 * Working Men's Club and Institute Union, an association of social clubs in the United Kingdom
 * Chippewa County International Airport in Sault Ste. Marie, Michigan (IATA Code: CIU)
 * Columbia International University, a Bible college and seminary in Columbia, South Carolina
 * Cyprus International University, Cyprus, North Cyprus
 * Cape plc, a construction company listed in the Alternative Investment Market under ticker CIU
 * Customs and Immigration Union (Canada)
 * Chronic idiopathic urticaria, also known as hives
 * Collective investment undertaking, another term for an investment fund
 * Conviction Integrity Unit, a division of a prosecutorial office, working to prevent, identify, and remedy false convictions
 * Cédula de Identidad de Uruguay, the Uruguayan identity card
 * Convergència i Unió, a Catalan political party