Gordon McKie has left his position as chief executive of the Scottish Rugby Union.
McKie last week won a confidence vote from the present board after an emergency meeting at Murrayfield.
That was held after media speculation suggesting that McKie would be leaving after six years in the job.
But the SRU has now confirmed in a statement that he is exiting Scottish rugby's governing body "with immediate effect".
However, it did not indicate whether McKie resigned or had been forced to quit.
McKie, an accountant by profession, has reduced the SRU's overdraft from £20m to about £15m since taking charge.
And he said: "I will look back on my time at Murrayfield with a real sense of pride as much has been achieved since the dark days of 2005.
"I very much appreciated the board's recent unanimous vote of confidence in the executive management team and I take this opportunity to thank them for their continued support.
"However, from a personal perspective, I instigated discussions last weekend after considering matters with my family, as the time is right for me to leave Scottish Rugby and move on to fresh challenges."
McKie in March announced Scotland's first performance review since 2007 after expressing dismay at "unacceptable" displays by the national team in the Six Nations.
He was also concerned about the showing of the two professional sides in a Magners League season during which Edinburgh coach Rob Moffat was sacked.
McKie had himself come in for some criticism about his own decisions and later this month was due to start working under a new chairman, the former chief executive of the FirstGroup transport firm, Sir Moir Lockhead.
Now senior non-executive director and former international Jock Millican will take the role as chief executive on an interim basis until a successor is appointed, with the recruitment process having already started.
Present chairman Allan Munro said: "Gordon has provided great leadership, accountability, stability and transformed Scottish Rugby in the past six years.
"He has achieved a great deal during his time as chief executive and, on behalf of the board and the staff, we thank him sincerely for his extensive efforts in leading the development of our sport at all levels and rebuilding our reputation amongst many of our key stakeholders.
"Specifically, since his appointment in August 2005, we have made great progress under his stewardship and enjoyed some significant highs in recent years, including the growth in the number of people playing the game, achieving our highest-ever world ranking position of sixth, enjoying notable wins at home and abroad for our national team and securing strong partnerships with sponsors and public sector partners.
"Gordon has demonstrated a willingness and an ability to support the board in the implementation of tough decisions that required to be made in the best interests of the game.
"Unlike 2005, when Scottish Rugby was close to insolvency, he leaves behind a solid platform and a stable financial base with significantly reduced debt, from which the next phase of developing the game in Scotland can be launched."