Banking and finance workers were worst affected although half of civil service offices are also being hit, research for the TUC found.
The main cause of RSI is the use of visual display units, the survey of safety officers in 7,000 workplaces showed.
A special TUC conference called on designers to help prevent RSI and help sufferers back to work.
Dick Pickering, a general council member, said: "RSI is caused by badly designed tools, equipment and conditions. Workers should be protected from the causes of RSI, and designers have a key role to play. They should be designing so that jobs fit the workers, rather than fitting the workers to the job."
RSI affects between 100,000 and 200,000 workers every year and costs industry pounds 1bn a year in sick pay and lost production, the TUC estimated.Reuse content