Patient care at Aberdeen Royal Infirmary faces a "serious impact" if problems are not "urgently addressed", a report has said.
The Healthcare Improvement Scotland (HIS) review made 13 recommendations for improvement for NHS Grampian.
It identified concerns about leadership and culture which are impacting on the quality of care.
The review was one of three critical reports into health care in the north east of Scotland published on Tuesday.
Following their publication, the whistleblower who went direct to the Scottish government to raise concerns about NHS Grampian has revealed he has quit his post in frustration.
Speaking exclusively to BBC Scotland, cancer specialist Malcolm Loudon said staff at NHS Grampian were "like an elastic that is stretched almost to breaking point".
He also talked of a "toxic culture" with low morale, high staff turnover and sickness and "no feeling of shared values between management and between those who are actually delivering the services".
NHS Grampian has declined to comment on his accusations.
The Aberdeen Royal Infirmary (ARI) report said the potential for patient care and safety to be further compromised was overwhelmingly evident.
Findings of Healthcare Improvement Scotland reports
- Potential for patient care and safety to be further compromised is overwhelmingly evident
- There have been weaknesses in the leadership and management of the health board, the executive team and the senior management team at Aberdeen Royal Infirmary
- A small number of consultants have acted to undermine management and have exhibited poor behaviour
- Management of older patient flow and capacity in Aberdeen Royal Infirmary and Woodend Hospital is not fit for purpose and puts patient safety at risk
- Read the key points from the three reports
HIS also said the NHS Grampian board was insufficiently aware of problems facing ARI.
It described one of the surgical units as significantly dysfunctional.
Dr Angus Cameron, chairman of the review team, said: "The issues are serious."
NHS Grampian said it accepted all the recommendations in the three reports.
Interim chief executive Malcolm Wright said: "These reports highlight issues with leadership and management, culture and behaviour, accountability and governance within NHS Grampian.
"We take these reports extremely seriously and we accept the recommendations that the reports make."
Mr Wright expressed disappointment at serious concerns raised in the older people's report, and apologised to patients and their families.
He said: "This is undoubtedly a challenging time for NHS Grampian.
"These three reports have highlighted a range of issues requiring immediate attention.
"I am confident in the ability of my colleagues throughout this organisation to address these issues and deliver a sustainable high quality health service for the future."
'Failings of leadership'
Niall Dickson, chief executive of the General Medical Council (GMC), said: "This report raises very serious issues about aspects of medical care at Aberdeen Royal Infirmary.
"In particular, those conducting the review found unprofessional conduct by senior doctors which had not been addressed, a significantly dysfunctional surgical unit, little evidence of effective performance management and a failure to follow up concerns raised by the GMC's survey of doctors in training at the hospital.
'We are also extremely concerned that large numbers of consultants had no job plans and there was minimal evidence that clinical governance structures were working effectively.
"The individual behaviours and the systemic failures described in the report are completely unacceptable.
"And while HIS found no direct evidence of patient harm, we agree with the authors when they conclude that 'the potential for patient care and safety to be further compromised is overwhelmingly evident in the findings of this report'."
Royal College of Nursing (RCN) Scotland associate director Ellen Hudson said: "We have been raising serious concerns both locally and nationally about the situation at Aberdeen Royal Infirmary for quite some time.
"These have now been exposed with the publication of this report by HIS, which lays bare the failings of leadership and management at NHS Grampian."
The health board's chief executive and medical director have left their posts in recent months as the row between management and senior consultants deepened.