A population-based series of 4,764 women from Piedmont, Italy, who were diagnosed with breast cancer during 1979-81 and for whom information on social and demographic factors was available, was followed-up for mortality until 1986 or 1987. Relative survival rates at one, three, and five years were 94.6, 81.6, and 71.1 percent, respectively, and were similar to those of other European series. Women aged 40-49 years at diagnosis experienced a better survival than women in other age groups. The mortality was highest between one and four years after diagnosis, and lowest between five and seven years. Survival rates were lowest for women above the age of 80, and single women had a worse prognosis than married women. Women with less than seven years of education had nonsignificantly lower survival rates than more educated women. No difference in survival was found according to occupation, size of town of residence, place of birth, or type of hospital.