Hundreds of staff working for Royal Cornwall Hospitals Trust are to be balloted for strike action in a row over job cuts and offshoring.
It follows a decision by the trust to send typing work abroad, while local workers are facing redundancies.
It comes two weeks after 400 workers were told that their jobs were at risk because of the trust's multimillion-pound budget deficit, reports the BBC.
Hundreds of Unison union members will be asked to vote on whether to start a campaign of industrial action.
A union spokesman said the trust had issued the letters while an outsourcing trial was carried out by the US-owned company Dictate IT. It is thought the plans involved sending the work electronically to India.
Christine Dayus, the union's South West regional officer, said: "We have tried to work with the trust to minimise redundancies. However, we now find out that it is planning to send work abroad while making local staff redundant."
The union also expressed concern at the quality of the work undertaken abroad.
In a statement, the trust said the outsourced transcription service trial was one of three options being considered as part of a review of clinical administrative support.
It said unions would be invited to undertake a full and robust review of the pilot.