Members of BECTU have begun voting in elections for the post of President, and seats on the National Executive Committee.
Ballot papers should start arriving at members' homes by March 18, and voting will close on April 28.
The results of all the ballots will then remain secret until the union's Annual Conference on May 21, which is being held in Eastbourne this year.
There are contests for NEC seats in three of the union's six industrial divisions, including the BBC, where Tony Lennon is also standing as a candidate.
This year's election is the third open contest for the President's post since the union's constitution was changed to comply with new labour laws which demand the position should be filled by a secret postal vote of the union's 28,000 members.
Tony Lennon stood in both previous elections, in 2002 and 2004, successfully winning the Presidency on both occasions.
