The main objective was the development of guidelines for future research in multiple sclerosis epidemiology. The project focused on epidemiological trends, methodological advances for analytical studies, genetic studies, and studies of the course of the disease. The work shows that epidemiology will be a key to understanding the MS puzzle. As the condition is so rare, affecting 1 in 1,000 people, systematic observations of environmental factors in large, ethnically defined populations are needed to uncover external factors influencing disease development. The project contributed to the standardisation and improvement of scientific methods, both for established and new research communities, for example in Russia and India.