The chances of having a fatal or serious accident were considered "high" or "medium-high" on 8% of the country's motorways and A-roads, according to the Road Safety Foundation, which carried out an analysis based on accident data from 2007-2009 compared to traffic levels.
This represents a significant improvement on three years earlier, when 16% of the network fell into this category, a change driven especially by improvements to Scotland's motorways, including better lighting and signage.
Among the success stories the RSF pointed to were the notorious "Cumberland Gap" section of the M6, immediately south of the A74(M) at the Scottish border, a six-mile stretch that has become the UK's second most improved road in safety ratings after being upgraded to motorway status in 2008.
The upgrade removed the last section of non-motorway road between central Scotland and eastern Europe.
It saw a dramatic drop in deaths and serious accidents from 15 in 2006-8 to just two in 2007-9.
The M8 between jct 8 at Coatbridge and jct 31 at Bishopton has also seen a 51% drop in the number of fatal and serious accidents.
This followed carriageway resurfacing, improvements to central safety barriers and installing anti-skid surfacing.
Nearly a third of Scotland's primary road network was deemed to present a medium or high risk of suffering a serious accident, compared to 2004-6, when 45% of these key roads were in these categories and only 1% of the network fell into the highest risk group.
This compared poorly to the UK average of 28% of key roads falling into the medium or high risk category, a shortfall partly explained by the higher number of single carriageway A roads in Scotland, which are considerably more dangerous than motorways.
Joanne Hill, director of the Road Safety Foundation said: "The lesson of the 'Cumberland Gap' is that motorways are Britain's safest roads and that there are safety dividends from upgrading deficits in safety features on busy dual carriageways."