The Road Safety Foundation reported that one in eight A roads north of the Border - 12 per cent - have an "unacceptably high risk" compared to one in ten across Britain.
They included 3 per cent of Scottish A roads being ranked in the highest risk category, compared to 2 per cent in Britain.
Scotland also accounted for one in nine of all British fatal crashes. The 14-mile A819 between Inveraray and Dalmally in Argyll was rated as Scotland's most dangerous main road. It had 12 crashes causing deaths or serious injuries from 2006-8 - nearly three-quarters more than in the previous three years.
The foundation attributed Scotland's poor showing to its high proportion of rural, single carriageway roads, where drivers face six times the risk compared to motorways and twice that of dual carriageways.
The report, which covered 28,000 miles of roads, found the proportions of head-on collisions and vehicles crashing off the road in Scotland was among the highest in Britain, with collisions at junctions the lowest.
Other high-risk Scottish roads included the A822 between Gilmerton, near Crieff, and Dunkeld, in Perth and Kinross, and A708 between Selkirk in the Borders and Moffat in Dumfries and Galloway.
However, Scottish roads did not feature among Britain's worst ten, which was topped by the A573 between Macclesfield in Cheshire and Buxton in Derbyshire.
Road Safety Foundation director Dr Joanne Hill said: "As the road budget becomes tighter, emphasis must be on saving lives with less.
"This year's report shows that not only can Britain reduce roads deaths and serious injuries but that, by targeting a relatively small mileage of high-risk roads, we can do so with good economic returns.
"Too often we pay for emergency services, hospitals and care for the disabled rather than taking easy steps to put road design faults right.
"Simple, relatively inexpensive engineering measures, such as improvements to signing and lining, resurfacing and the layout of signals at junctions, are paying dividends and are affordable, particularly when done as part of well-planned routine maintenance."
Motoring groups warned that spending cuts must not threaten road safety improvements.
Neil Greig, policy and research director for the Institute of Advanced Motorists, said: "It should be no surprise that Scotland, with its high proportion of single carriageway rural roads has the highest average risk.
"The Scottish Government should use the information in this survey to target resources at the worst locations and routes.
Automobile Association president Edmund King said: "This report shows road safety should be able to continue to improve during the current period of austerity. Dangerous stretches must be targeted - with both engineering and education-backed enforcement.
"This will be much more effective than any kind of blanket restriction on either urban or rural roads.
Transport Minister Stewart Stevenson said: "Statistics published last week show Scotland has the lowest road casualties in Scotland in 60 years, a welcome drop that continues a downward trend in recent years.
"[Scottish Government agency] Transport Scotland assesses the safety performance of trunk roads every year to identify specific locations on the network which might benefit from localised engineering improvements."