NHS Highland bosses have been branded "incompetent" after auditors found £200,000 of payments made for services without a legal contract.
Failings were found in two sample checks carried out by Audit Scotland which has now ordered health board directors to examine all contracts.
Auditors examined secondary care for vasectomies and a deal with Nairn Medical Centre, and problems were highlighted in both.
The Nairn contract, which has been in place since 1998, is now worth £200,000 per year, but there is no evidence of an original legal agreement or tendering process.
Auditors also noted that the contract was terminated by NHS Highland in May 2016 for reasons that were "unclear", before then being reinstated following a complaint by the medical centre.
The situation has led Audit Scotland to question whether cash-strapped NHS Highland is getting value for money as Highlands and Islands Conservative MSP Edward Mountain called the revelations "scandalous" and questioned the potential scale of the issue.
"Audit Scotland looked at two primary care contracts which had been running for years unaudited and undocumented and there was no formal contract for it, they just paid it every year," he said.
"It’s scandalous quite frankly. If I had been paying £200,000 every year without any contracts it would be called incompetent and that is exactly what it is, incompetence.
"If this is what they found from looking at two instances, how many more are there?"
In an official response NHS directors pledged to review the Nairn contract and any new ones when the current agreement expires in September.
The audit also recommended reviewing all contracts for vasectomy services carried out outwith Raigmore Hospital, saying current arrangements and performance monitoring is "inconsistent".
An NHS Highland spokesman said: "The report is now in the public domain, including our response on the matter.
"The required management actions are being taken to implement the recommendations and will be monitored via our audit committee."
The findings come after First Minister Nicola Sturgeon confirmed all health boards in Scotland are under the spotlight.
NHS Highland was the first to be reviewed as a pilot but others will be examined to ensure they are up to the task of steering health authorities through the integration of health and social care.
This involves health boards and local authorities working in partnership, meaning the NHS reports to the council on issues relating to adult care while the council is answerable to the NHS on issues relating to children and families.
NHS Highland and Highland Council were the first to integrate five years ago.