Patrick Spence was a 14-year RIM veteran widely considered a rising star. A spokeswoman for RIM said Spence's last day with the company will be June 15.
Spence was promoted to the global sales role in July after serving as managing director for Europe, the Middle East and Africa.
A source close to the company told the Globe and Mail newspaper that Spence likely stepped down after being passed over for the chief operating officer role recently filled by Kristian Tear, who spent most of his career at Sony Corp, Ericsson, and their Sony Ericsson mobile phone joint venture.
Tear's role covers operational functions for handhelds and services, including research and development, global sales, manufacturing and supply chain management.
RIM has seen a steady stream of departures in the past year as its once-dominant market share has slipped amid fierce competition from Apple Inc and phones running on Google Inc's Android software.
London-based Spence helped launch a range of BlackBerry 7 devices last year and had also worked to decentralize RIM's sales planning so it fit better with regional sensibilities.
Spence joined RIM soon after graduating from the University of Western Ontario, before the company had created its first BlackBerry smartphone.
RIM spokeswoman Tenille Kennedy said the sales function will report directly to Chief Executive Thorsten Heins on an interim basis before coming under Tear when he starts work in coming months. RIM did not name a replacement for Spence or say where he was going.
Heins replaced longtime co-CEOs Mike Lazaridis and Jim Balsillie, who stepped down in January, and has moved quickly to clear house. Other key executives have also exited the company in the past year.
A chief operating officer, Jim Rowan, and head of software David Yach left in March, at the same time that Balsillie left the board. Other recent departures include Alan Brenner, a senior vice president for the BlackBerry platform, and Alistair Mitchell, a vice president for the BlackBerry Messenger instant messaging product.
The head of RIM's India unit left in November, its head of government relations left months before that, and former chief marketing officer Keith Pardy departed more than a year ago.
RIM said this month it had replaced Pardy with wireless veteran Frank Boulben, who has yet to start work.
Analysts expect RIM to struggle to sell its legacy devices - widely considered inferior to Apple's latest iPhone and high-end Android devices - for several quarters ahead of the planned launch of next-generation BlackBerry 10 phones later this year.
In July, RIM slashed 2,000 jobs, or about 11 percent of its workforce, to cut costs as sales and profit fell. [ID:nL3E7IP251] Its developer relations and sales and marketing teams were particularly hard hit.
The company posted a loss in its most recent quarter on the back of a writedown on unsold inventory and a slump in phone shipments.
RIM shares have fallen more than 80 percent from a peak of almost $70 in February 2011, to close at $11.09 on the Nasdaq on Wednesday.
(Reporting by Alastair Sharp in Toronto; Editing by Carol Bishopric and Richard Pullin)
By Alastair Sharp