Thousands of workers at the BBC went on strike on Monday to protest against plans to get rid of 3,780 jobs.
The strike means that some live TV and radio programmes will not be broadcast. The walk-out started at midnight and will last 24 hours.
The BBC says the job cuts are necessary so more money can be put into making programmes. Trade Unions say the cuts are the worst in the BBC's history.
Workers are expected to walk out again on 31 May and 1 June.
Some striking Union members have set up pickets around BBC buildings, and staff are gathering to protest against the changes.
The BBC's news programmes are expected to be worst affected by the walk out.