The government department tasked with the unenviable job of overseeing Brexit negotiations, as well as establishing any future relationship between the UK and EU, has lost around one fifth of its workforce since launch.
A total of 125 employees working at the Department for Exiting the European Union (DExEU) have left since it was created 14 months ago, with just 482 civil servants remaining.
The figures were revealed following an Freedom of Information request from Bloomberg, but the data only included 124 people who left up until 18 August.
Since then, the government's top Brexit official Oliver Robbins has also left the department to take on another role at the Cabinet Office, working more directly with Prime Minister Theresa May on Brexit.
It was reported that Robbins left his role as top civil servant at DExEU on September after a fallout with Brexit secretary David Davis.
In January, Sir Ivan Rogers also resigned as the UK's ambassador to the European Union. In his resignation letter, he told civil servants working at the department to continue to "challenge ill-founded arguments and muddled thinking" with regards to Brexit negations.
Rogers was eventually replaced by the UK's ambassador to Russia and the Ukraine Sir Tim Barrow.
In response to the figures, the DExEU told Bloomberg that fewer than one in five workers had fully left the civil service and many simply moved elsewhere to another government department because their "loan, contract or fast stream rotation ended".
A spokesperson added: "Given the large majority of these changes were the result of normal civil service rotation or the end of defined loan periods, these roles were quickly filled."
Following Robbins' departure, Labour's shadow Brexit secretary Sir Kier Starmer said: "Moving key individuals at this critical time adds a whole new dimension to the government's chaotic approach to Brexit.
"Deep divisions in the cabinet and a complete lack of leadership are putting the national interest at risk."