US Health Secretary Tom Price has resigned over the use of expensive private planes for official business.
He previously apologised after making 26 private flights since May at a cost of $400,000 (£300,000) to taxpayers.
Government officials, except those dealing with national security matters, are required to take commercial flights for work related travel.
Three other members of President Donald Trump's cabinet are under scrutiny for using private planes while working.
A White House statement said President Trump had accepted Mr Price's resignation, adding that Don J Wright had been designated as acting health secretary. Mr Wright is currently deputy assistant secretary for health.
In his letter of resignation, seen by the New York Times, Mr Price said he regretted that "recent events have created a distraction" from the work of the health department.
An investigation by the political news website Politico found that Mr Price's travels had cost more than $1m (£750,000).
As well as the $400,000 for private flights, that figure includes the cost of military aircraft used for Mr Price's trips abroad, Politico added.
President Trump had earlier said he was "not happy" with the expense.
Mr Price had promised to repay the cost of his seats on private flights, saying: "The taxpayers won't pay a dime for my seat on those planes."
Source: BBC