The research is assessed by peer review panels
The quality of research produced by Scottish universities has reached new heights, according to a study.
An independent review said the country's share of UK research rated as internationally excellent or better had gone up from 11.6% to 12.3% since 2001.
The results were revealed as part of the Research Assessment Exercise (RAE).
The RAE, carried out by peer review panels, is used to assess the standard of research for all subjects and allocate £1.5bn of university funding.
The study showed that every university in Scotland produced at least some research which was judged to be "world-leading".
The data grades university research using a star system, where four stars denotes research that is of world-leading quality.
A three-star grading denotes research that is internationally excellent, while two stars means the research is recognised internationally and one star denotes research that is nationally recognised.
The University of Edinburgh came top in Scotland with 63% of research activity given four or three stars.
It was rated best in the UK for medicine, IT and linguistics.
The University of Glasgow claims it came out joint-top in the UK for veterinary sciences with The Royal Veterinary College, London, sharing a grade point average of 2.5.
But Edinburgh Vet School claims to be the best with the highest percentage of "world leading research".
St Andrews, University of Aberdeen and the University of Dundee completed the top five in Scotland.
In total, 1,000 Scottish researchers and their supporting teams were considered to be leading the world.
Edinburgh University principal, Prof Sir Timothy O'Shea, said: "Research at the University of Edinburgh is constantly expanding the depth of human knowledge and making an impact on the wider world, improving the quality of life for people in Scotland and further afield."
Sir Muir Russell, principal of University of Glasgow, said: "Our results show the strength of research at this university.
"We have performed extremely well across our wide disciplines and this is a reflection of the strategy that we have pursued to build a team of internationally recognised researchers in Glasgow."
The principal and vice-chancellor of St Andrews University, Dr Brian Lang, said: "The results of RAE 2008 are a credit to St Andrews.
"It confirms that St Andrews remains one of the best and most research-intensive universities in the UK and one of the most active in that spectrum of research deemed world leading or excellent by international standards."
Education Secretary Fiona Hyslop said: "Today is a real opportunity to celebrate the exciting and innovative work which goes on in our universities across Scotland every day - research which greatly contributes to our efforts to create a smarter, fairer, healthier, wealthier and greener Scotland.
"The results reflect that hard work, the efforts of those working in our universities and the substantial investment which we are making in the sector - currently more than £1bn a year."
At the other end of the scale, Queen Margaret University Edinburgh was ranked the worst research institution in Scotland for research and the third worst in the UK.
Prof Anton Muscatelli, of Universities Scotland, said: "At a time of poor world economic news, we have this tremendously encouraging news about something we in Scotland do exceptionally well.
"The results aren't just about the economy. The work these findings measure will result in major breakthroughs in health, energy, culture, information management, environmental technology and many other fields which will change people's lives for the better."
In March the government announced plans to replace the RAE after 2008 with what is known as a metrics-based system.
The new process will use a set of indicators based on research income, postgraduate numbers and a measure of quality to set out the basis by which research funds will be distributed.
It is anticipated that all subjects will be assessed by the new system by 2014.