CTT

CTT may refer to:
 * CTT Correios de Portugal, S.A., the national postal service of Portugal
 * CTT (Macau), the Macau Post Office
 * Cycling Time Trials, the governing body for time trialling in the UK
 * Classical test theory
 * Columbia TriStar Television
 * ConcurTaskTrees
 * Custom Air Transport's ICAO code
 * CTT, a specialty certification of Comp TIA
 * CTT, a codon for the amino acid Leucine
 * × Cattlianthe (Ctt.), a nothogenus of orchids