The Union of Communication Workers (UCW) was a trade union in the United Kingdom for workers in the post office and telecommunications industries.
The union was founded in 1919 as the Union of Post Office Workers (UPW) by the merger of the Postmen's Federation, Postal and Telegraph Clerks' Association and the Fawcett Association. It achieved official recognition, and as a result, in 1920 the London Postal Porters' Association, Central London Postmen's Association, Tracers' Association, Tube Staff Association, Messengers' Association and Sorters' Association all merged with it. It was banned legally from TUC membership from 1927 to 1946. Its longest strike was for 7 weeks in 1971.
It changed its name in 1980, and merged with the National Communications Union in 1995 to form the Communication Workers' Union.
The union sponsored Labour Party candidates in each Parliamentary election. From 1927 until the end of World War II, the union was legally barred from affiliating to the party, so its candidates in that period are omitted from many sources.