The objective of this study, part of the wider EUROCARE II collaborative project, was to examine variations by age and country in the relative survival of women from breast cancer in Europe, based on data fro 145,000 cases in 1985-1989 and trends based on (245,000) cases for 1978-1989. Data were supplied by 42 cancer registries in 17 countries to a common protocol. Results for some countries where the participating registries covered only small proportions of the total population may not be representative of the whole country. In 1985-1989 there were wide differences among the 17 countries: survival was above the European average in Iceland, Finland, Sweden, Switzerland, France and Italy; around average in Denmark, The Netherlands, Germany and Spain; below average in Scotland, England and Slovenia; and well below average in Slovakia, Poland and Estonia. In France, Spain and Italy, but not in the U.K., there were wide differences in survival among the participating registries. Survival generally declined with age, particularly in the elderly (75 years and over)--this was most marked in Denmark, Scotland and England. Over the period 1978-1989, 1-year survival improved by 2% overall and 5-year survival by 6%. There were improvements in 5-year survival in all countries except Iceland, Germany, Switzerland and Estonia, and in all age groups except the youngest (15-44 years). It is likely that differences in the access to and quality of care in the various countries played a large part in explaining the differences in survival.