Uber president Jeff Jones has quit after just six months saying his experience of the company was incompatible with his own "beliefs and approach to leadership".
The departure of Mr Jones is the latest blow to the taxi app after a series of controversies.
His role had been called into question after Uber launched a search for a chief operating officer alongside chief executive Travis Kalanick.
Mr Jones, a marketing expert, had been tasked with overseeing the bulk of Uber's global operations since joining last August.
He had previously worked for Target, and was credited with modernising the US retailer's brand.
Mr Jones said: "I joined Uber because of its mission, and the challenge to build global capabilities that would help the company mature and thrive long term.
"It is now clear, however, that the beliefs and approach to leadership that have guided my career are inconsistent with what I saw and experienced at Uber, and I can no longer continue as president of the ride-sharing business."
Uber said: "We want to thank Jeff for his six months at the company and wish him all the best."
It follows a series of recent controversies including claims of sexual harassment at the company - which prompted an internal investigation.
There was also the release of a video showing Mr Kalanick berating an Uber driver who had complained about cuts to rates paid to drivers, prompting him to make a public apology.
Meanwhile, Uber is facing a lawsuit from Google parent Alphabet (Xetra: ABEA.DE - news) 's self-driving car division, which has accused it of stealing designs for autonomous car technology. Uber has said the claims are false.
Earlier this month, the company lost a court battle in the UK over rules forcing its drivers to prove their reading and writing skills in English to operate in London.