The effects of genetics and lifestyle on health are to be examined as part of a multi-million pound 20-year study.
Volunteers have been signing up to have their health monitored
Researchers plan to recruit 50,000 people to take part in Generation Scotland, one of the largest-ever family healthcare projects in the UK.
Doctors and scientists hope that by creating a huge database of patient information they can pinpoint who is more susceptible to common conditions.
People can joins the project via the Generation Scotland website.
The project will give data on heart disease, cancer and mental illness.
If successful, it could help identify those at high risk of developing genetic conditions and lead to the development of early treatment with new drugs.
Scottish families are now signing up for the project, involving leading doctors and academics from Aberdeen, Dundee, Edinburgh and Glasgow universities.
Professor Andrew Morris from Dundee University is chairman of the Generation Scotland scientific committee.
He said: "We need to understand how people's genes work with environmental issues such as diet and smoking, and why some people develop certain problems while others remain healthy.
"We are delighted that after years of careful preparation we are in a position to create a uniquely Scottish resource of the highest international standing, which has the potential to shape everyday clinical care and modern public health strategies."
The study is being funded by the Scottish Executive and the Scottish Funding Council.
Its first phase lasts two-and-a-half years at a cost of £6.2m.
Edinburgh University's Professor David Porteous said: "Generation Scotland brings together all the research experts across Scotland in a ground-breaking and hugely ambitious collaboration with the NHS and the people of Scotland."
Health Minister Andy Kerr welcomed the project.
The minister said: "If we can identify groups of people at risk of particular conditions, such as heart disease, osteoporosis or mental illness, we can give them the support they need early in life to avoid problems."
One of the first people to take part in the study was service engineer Alex Whyte from Dundee.
Mr Whyte, 64, became involved after his daughter, Fiona, was told about it at her diabetic clinic at Ninewells Hospital in Dundee.
Now the whole family, including Mr Whyte's wife, Agnes and their other daughter, Louise, have had their details recorded.
"It is really interesting to see what they are doing and I am wholly supportive of it," he said.
"If this is as successful as the people behind believe then they may be able to develop cures for some diseases in the future."